nlohmann::basic_json
json.hpp
template< typename U, typename V, typename... Args > class ObjectType ObjectType std::map
template< typename U, typename... Args > class ArrayType ArrayType std::vector
class StringType std::string
class BooleanType bool
class NumberIntegerType std::int64_t
class NumberUnsignedType std::uint64_t
class NumberFloatType double
template< typename U > class AllocatorType AllocatorType std::allocator
template< typename T, typename SFINAE=void > class JSONSerializer JSONSerializer adl_serializer
class BinaryType std::vector<std::uint8_t>
exceptions

Classes to implement user-defined exceptions.

detail::exception using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::exception = detail::exception exception

general exception of the basic_json class

This class is an extension of `std::exception` objects with a member id for exception ids. It is used as the base class for all exceptions thrown by the basic_json class. This class can hence be used as "wildcard" to catch exceptions.

Subclasses:

- parse_error for exceptions indicating a parse error

- invalid_iterator for exceptions indicating errors with iterators

- type_error for exceptions indicating executing a member function with a wrong type

- out_of_range for exceptions indicating access out of the defined range

- other_error for exceptions indicating other library errors

{The following code shows how arbitrary library exceptions can be caught.,exception}

version 3.0.0

detail::parse_error using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parse_error = detail::parse_error parse_error

exception indicating a parse error

This exception is thrown by the library when a parse error occurs. Parse errors can occur during the deserialization of JSON text, CBOR, MessagePack, as well as when using JSON Patch.

Member byte holds the byte index of the last read character in the input file.

Exceptions have ids 1xx.

name / id | example message | description
json.exception.parse_error.101 | parse error at 2: unexpected end of input; expected string literal | This error indicates a syntax error while deserializing a JSON text. The error message describes that an unexpected token (character) was encountered, and the member byte indicates the error position.
json.exception.parse_error.102 | parse error at 14: missing or wrong low surrogate | JSON uses the `\uxxxx` format to describe Unicode characters. Code points above above 0xFFFF are split into two `\uxxxx` entries ("surrogate pairs"). This error indicates that the surrogate pair is incomplete or contains an invalid code point.
json.exception.parse_error.103 | parse error: code points above 0x10FFFF are invalid | Unicode supports code points up to 0x10FFFF. Code points above 0x10FFFF are invalid.
json.exception.parse_error.104 | parse error: JSON patch must be an array of objects | RFC 6902 requires a JSON Patch document to be a JSON document that represents an array of objects.
json.exception.parse_error.105 | parse error: operation must have string member 'op' | An operation of a JSON Patch document must contain exactly one "op" member, whose value indicates the operation to perform. Its value must be one of "add", "remove", "replace", "move", "copy", or "test"; other values are errors.
json.exception.parse_error.106 | parse error: array index '01' must not begin with '0' | An array index in a JSON Pointer (RFC 6901) may be `0` or any number without a leading `0`.
json.exception.parse_error.107 | parse error: JSON pointer must be empty or begin with '/' - was: 'foo' | A JSON Pointer must be a Unicode string containing a sequence of zero or more reference tokens, each prefixed by a `/` character.
json.exception.parse_error.108 | parse error: escape character '~' must be followed with '0' or '1' | In a JSON Pointer, only `~0` and `~1` are valid escape sequences.
json.exception.parse_error.109 | parse error: array index 'one' is not a number | A JSON Pointer array index must be a number.
json.exception.parse_error.110 | parse error at 1: cannot read 2 bytes from vector | When parsing CBOR or MessagePack, the byte vector ends before the complete value has been read.
json.exception.parse_error.112 | parse error at 1: error reading CBOR; last byte: 0xF8 | Not all types of CBOR or MessagePack are supported. This exception occurs if an unsupported byte was read.
json.exception.parse_error.113 | parse error at 2: expected a CBOR string; last byte: 0x98 | While parsing a map key, a value that is not a string has been read.
json.exception.parse_error.114 | parse error: Unsupported BSON record type 0x0F | The parsing of the corresponding BSON record type is not implemented (yet).
json.exception.parse_error.115 | parse error at byte 5: syntax error while parsing UBJSON high-precision number: invalid number text: 1A | A UBJSON high-precision number could not be parsed.

For an input with n bytes, 1 is the index of the first character and n+1 is the index of the terminating null byte or the end of file. This also holds true when reading a byte vector (CBOR or MessagePack).

{The following code shows how a `parse_error` exception can be caught.,parse_error}

- exception for the base class of the library exceptions

- invalid_iterator for exceptions indicating errors with iterators

- type_error for exceptions indicating executing a member function with a wrong type

- out_of_range for exceptions indicating access out of the defined range

- other_error for exceptions indicating other library errors

version 3.0.0

detail::invalid_iterator using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::invalid_iterator = detail::invalid_iterator invalid_iterator

exception indicating errors with iterators

This exception is thrown if iterators passed to a library function do not match the expected semantics.

Exceptions have ids 2xx.

name / id | example message | description
json.exception.invalid_iterator.201 | iterators are not compatible | The iterators passed to constructor basic_json(InputIT first, InputIT last) are not compatible, meaning they do not belong to the same container. Therefore, the range (first, last) is invalid.
json.exception.invalid_iterator.202 | iterator does not fit current value | In an erase or insert function, the passed iterator pos does not belong to the JSON value for which the function was called. It hence does not define a valid position for the deletion/insertion.
json.exception.invalid_iterator.203 | iterators do not fit current value | Either iterator passed to function erase(IteratorType first, IteratorType last) does not belong to the JSON value from which values shall be erased. It hence does not define a valid range to delete values from.
json.exception.invalid_iterator.204 | iterators out of range | When an iterator range for a primitive type (number, boolean, or string) is passed to a constructor or an erase function, this range has to be exactly (begin(), end()), because this is the only way the single stored value is expressed. All other ranges are invalid.
json.exception.invalid_iterator.205 | iterator out of range | When an iterator for a primitive type (number, boolean, or string) is passed to an erase function, the iterator has to be the begin() iterator, because it is the only way to address the stored value. All other iterators are invalid.
json.exception.invalid_iterator.206 | cannot construct with iterators from null | The iterators passed to constructor basic_json(InputIT first, InputIT last) belong to a JSON null value and hence to not define a valid range.
json.exception.invalid_iterator.207 | cannot use key() for non-object iterators | The key() member function can only be used on iterators belonging to a JSON object, because other types do not have a concept of a key.
json.exception.invalid_iterator.208 | cannot use operator[] for object iterators | The operator[] to specify a concrete offset cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
json.exception.invalid_iterator.209 | cannot use offsets with object iterators | The offset operators (+, -, +=, -=) cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
json.exception.invalid_iterator.210 | iterators do not fit | The iterator range passed to the insert function are not compatible, meaning they do not belong to the same container. Therefore, the range (first, last) is invalid.
json.exception.invalid_iterator.211 | passed iterators may not belong to container | The iterator range passed to the insert function must not be a subrange of the container to insert to.
json.exception.invalid_iterator.212 | cannot compare iterators of different containers | When two iterators are compared, they must belong to the same container.
json.exception.invalid_iterator.213 | cannot compare order of object iterators | The order of object iterators cannot be compared, because JSON objects are unordered.
json.exception.invalid_iterator.214 | cannot get value | Cannot get value for iterator: Either the iterator belongs to a null value or it is an iterator to a primitive type (number, boolean, or string), but the iterator is different to begin().

{The following code shows how an `invalid_iterator` exception can be caught.,invalid_iterator}

- exception for the base class of the library exceptions

- parse_error for exceptions indicating a parse error

- type_error for exceptions indicating executing a member function with a wrong type

- out_of_range for exceptions indicating access out of the defined range

- other_error for exceptions indicating other library errors

version 3.0.0

detail::type_error using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::type_error = detail::type_error type_error

exception indicating executing a member function with a wrong type

This exception is thrown in case of a type error; that is, a library function is executed on a JSON value whose type does not match the expected semantics.

Exceptions have ids 3xx.

name / id | example message | description
json.exception.type_error.301 | cannot create object from initializer list | To create an object from an initializer list, the initializer list must consist only of a list of pairs whose first element is a string. When this constraint is violated, an array is created instead.
json.exception.type_error.302 | type must be object, but is array | During implicit or explicit value conversion, the JSON type must be compatible to the target type. For instance, a JSON string can only be converted into string types, but not into numbers or boolean types.
json.exception.type_error.303 | incompatible ReferenceType for get_ref, actual type is object | To retrieve a reference to a value stored in a basic_json object with get_ref, the type of the reference must match the value type. For instance, for a JSON array, the ReferenceType must be array_t &.
json.exception.type_error.304 | cannot use at() with string | The at() member functions can only be executed for certain JSON types.
json.exception.type_error.305 | cannot use operator[] with string | The operator[] member functions can only be executed for certain JSON types.
json.exception.type_error.306 | cannot use value() with string | The value() member functions can only be executed for certain JSON types.
json.exception.type_error.307 | cannot use erase() with string | The erase() member functions can only be executed for certain JSON types.
json.exception.type_error.308 | cannot use push_back() with string | The push_back() and operator+= member functions can only be executed for certain JSON types.
json.exception.type_error.309 | cannot use insert() with | The insert() member functions can only be executed for certain JSON types.
json.exception.type_error.310 | cannot use swap() with number | The swap() member functions can only be executed for certain JSON types.
json.exception.type_error.311 | cannot use emplace_back() with string | The emplace_back() member function can only be executed for certain JSON types.
json.exception.type_error.312 | cannot use update() with string | The update() member functions can only be executed for certain JSON types.
json.exception.type_error.313 | invalid value to unflatten | The unflatten function converts an object whose keys are JSON Pointers back into an arbitrary nested JSON value. The JSON Pointers must not overlap, because then the resulting value would not be well defined.
json.exception.type_error.314 | only objects can be unflattened | The unflatten function only works for an object whose keys are JSON Pointers.
json.exception.type_error.315 | values in object must be primitive | The unflatten function only works for an object whose keys are JSON Pointers and whose values are primitive.
json.exception.type_error.316 | invalid UTF-8 byte at index 10: 0x7E | The dump function only works with UTF-8 encoded strings; that is, if you assign a `std::string` to a JSON value, make sure it is UTF-8 encoded.
json.exception.type_error.317 | JSON value cannot be serialized to requested format | The dynamic type of the object cannot be represented in the requested serialization format (e.g. a raw `true` or `null` JSON object cannot be serialized to BSON)

{The following code shows how a `type_error` exception can be caught.,type_error}

- exception for the base class of the library exceptions

- parse_error for exceptions indicating a parse error

- invalid_iterator for exceptions indicating errors with iterators

- out_of_range for exceptions indicating access out of the defined range

- other_error for exceptions indicating other library errors

version 3.0.0

detail::out_of_range using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::out_of_range = detail::out_of_range out_of_range

exception indicating access out of the defined range

This exception is thrown in case a library function is called on an input parameter that exceeds the expected range, for instance in case of array indices or nonexisting object keys.

Exceptions have ids 4xx.

name / id | example message | description
json.exception.out_of_range.401 | array index 3 is out of range | The provided array index i is larger than size-1.
json.exception.out_of_range.402 | array index '-' (3) is out of range | The special array index `-` in a JSON Pointer never describes a valid element of the array, but the index past the end. That is, it can only be used to add elements at this position, but not to read it.
json.exception.out_of_range.403 | key 'foo' not found | The provided key was not found in the JSON object.
json.exception.out_of_range.404 | unresolved reference token 'foo' | A reference token in a JSON Pointer could not be resolved.
json.exception.out_of_range.405 | JSON pointer has no parent | The JSON Patch operations 'remove' and 'add' can not be applied to the root element of the JSON value.
json.exception.out_of_range.406 | number overflow parsing '10E1000' | A parsed number could not be stored as without changing it to NaN or INF.
json.exception.out_of_range.407 | number overflow serializing '9223372036854775808' | UBJSON and BSON only support integer numbers up to 9223372036854775807. (until version 3.8.0)
json.exception.out_of_range.408 | excessive array size: 8658170730974374167 | The size (following `#`) of an UBJSON array or object exceeds the maximal capacity.
json.exception.out_of_range.409 | BSON key cannot contain code point U+0000 (at byte 2) | Key identifiers to be serialized to BSON cannot contain code point U+0000, since the key is stored as zero-terminated c-string

{The following code shows how an `out_of_range` exception can be caught.,out_of_range}

- exception for the base class of the library exceptions

- parse_error for exceptions indicating a parse error

- invalid_iterator for exceptions indicating errors with iterators

- type_error for exceptions indicating executing a member function with a wrong type

- other_error for exceptions indicating other library errors

version 3.0.0

detail::other_error using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::other_error = detail::other_error other_error

exception indicating other library errors

This exception is thrown in case of errors that cannot be classified with the other exception types.

Exceptions have ids 5xx.

name / id | example message | description
json.exception.other_error.501 | unsuccessful: {"op":"test","path":"/baz", "value":"bar"} | A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.

- exception for the base class of the library exceptions

- parse_error for exceptions indicating a parse error

- invalid_iterator for exceptions indicating errors with iterators

- type_error for exceptions indicating executing a member function with a wrong type

- out_of_range for exceptions indicating access out of the defined range

{The following code shows how an `other_error` exception can be caught.,other_error}

version 3.0.0

container types

The canonic container types to use basic_json like any other STL container.

basic_json using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::value_type = basic_json value_type

the type of elements in a basic_json container

value_type & using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::reference = value_type& reference

the type of an element reference

const value_type & using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::const_reference = const value_type& const_reference

the type of an element const reference

std::ptrdiff_t using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::difference_type = std::ptrdiff_t difference_type

a type to represent differences between iterators

std::size_t using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::size_type = std::size_t size_type

a type to represent container sizes

AllocatorType< basic_json > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::allocator_type = AllocatorType<basic_json> allocator_type

the allocator type

typename std::allocator_traits< allocator_type >::pointer using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::pointer = typename std::allocator_traits<allocator_type>::pointer pointer

the type of an element pointer

typename std::allocator_traits< allocator_type >::const_pointer using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::const_pointer = typename std::allocator_traits<allocator_type>::const_pointer const_pointer

the type of an element const pointer

iter_impl< basic_json > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::iterator = iter_impl<basic_json> iterator

an iterator for a basic_json container

iter_impl< const basic_json > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::const_iterator = iter_impl<const basic_json> const_iterator

a const iterator for a basic_json container

json_reverse_iterator< typename basic_json::iterator > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::reverse_iterator = json_reverse_iterator<typename basic_json::iterator> reverse_iterator

a reverse iterator for a basic_json container

json_reverse_iterator< typename basic_json::const_iterator > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::const_reverse_iterator = json_reverse_iterator<typename basic_json::const_iterator> const_reverse_iterator

a const reverse iterator for a basic_json container

JSON value data types

The data types to store a JSON value. These types are derived from the template arguments passed to class basic_json.

std::less< StringType > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::object_comparator_t = std::less<StringType> object_comparator_t
ObjectType< StringType, basic_json, object_comparator_t, AllocatorType< std::pair< const StringType, basic_json > >> using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::object_t = ObjectType<StringType, basic_json, object_comparator_t, AllocatorType<std::pair<const StringType, basic_json> >> object_t

a type for an object

RFC 8259 describes JSON objects as follows:

> An object is an unordered collection of zero or more name/value pairs, where a name is a string and a value is a string, number, boolean, null, object, or array.

To store objects in C++, a type is defined by the template parameters described below.

ObjectType

the container to store objects (e.g., `std::map` or `std::unordered_map`)

StringType

the type of the keys or names (e.g., `std::string`). The comparison function `std::less<StringType>` is used to order elements inside the container.

AllocatorType

the allocator to use for objects (e.g., `std::allocator`)

Default type

With the default values for ObjectType (`std::map`), StringType (`std::string`), and AllocatorType (`std::allocator`), the default value for object_t is:

    std::map<
    std::string,//key_type
    basic_json,//value_type
    std::less<std::string>,//key_compare
    std::allocator<std::pair<conststd::string,basic_json>>//allocator_type
    >

Behavior

The choice of object_t influences the behavior of the JSON class. With the default type, objects have the following behavior:

- When all names are unique, objects will be interoperable in the sense that all software implementations receiving that object will agree on the name-value mappings.

- When the names within an object are not unique, it is unspecified which one of the values for a given key will be chosen. For instance, `{"key": 2, "key": 1}` could be equal to either `{"key": 1}` or `{"key": 2}`.

- Internally, name/value pairs are stored in lexicographical order of the names. Objects will also be serialized (see dump) in this order. For instance, `{"b": 1, "a": 2}` and `{"a": 2, "b": 1}` will be stored and serialized as `{"a": 2, "b": 1}`.

- When comparing objects, the order of the name/value pairs is irrelevant. This makes objects interoperable in the sense that they will not be affected by these differences. For instance, `{"b": 1, "a": 2}` and `{"a": 2, "b": 1}` will be treated as equal.

Limits

RFC 8259 specifies:

> An implementation may set limits on the maximum depth of nesting.

In this class, the object's limit of nesting is not explicitly constrained. However, a maximum depth of nesting may be introduced by the compiler or runtime environment. A theoretical limit can be queried by calling the max_size function of a JSON object.

Storage

Objects are stored as pointers in a basic_json type. That is, for any access to object values, a pointer of type `object_t*` must be dereferenced.

see array_t type for an array value

version 1.0.0

The order name/value pairs are added to the object is not preserved by the library. Therefore, iterating an object may return name/value pairs in a different order than they were originally stored. In fact, keys will be traversed in alphabetical order as `std::map` with `std::less` is used by default. Please note this behavior conforms to RFC 8259, because any order implements the specified "unordered" nature of JSON objects.

ArrayType< basic_json, AllocatorType< basic_json > > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::array_t = ArrayType<basic_json, AllocatorType<basic_json> > array_t

a type for an array

RFC 8259 describes JSON arrays as follows:

> An array is an ordered sequence of zero or more values.

To store objects in C++, a type is defined by the template parameters explained below.

ArrayType

container type to store arrays (e.g., `std::vector` or `std::list`)

AllocatorType

allocator to use for arrays (e.g., `std::allocator`)

Default type

With the default values for ArrayType (`std::vector`) and AllocatorType (`std::allocator`), the default value for array_t is:

    std::vector<
    basic_json,//value_type
    std::allocator<basic_json>//allocator_type
    >

Limits

RFC 8259 specifies:

> An implementation may set limits on the maximum depth of nesting.

In this class, the array's limit of nesting is not explicitly constrained. However, a maximum depth of nesting may be introduced by the compiler or runtime environment. A theoretical limit can be queried by calling the max_size function of a JSON array.

Storage

Arrays are stored as pointers in a basic_json type. That is, for any access to array values, a pointer of type `array_t*` must be dereferenced.

see object_t type for an object value

version 1.0.0

StringType using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::string_t = StringType string_t

a type for a string

RFC 8259 describes JSON strings as follows:

> A string is a sequence of zero or more Unicode characters.

To store objects in C++, a type is defined by the template parameter described below. Unicode values are split by the JSON class into byte-sized characters during deserialization.

StringType

the container to store strings (e.g., `std::string`). Note this container is used for keys/names in objects, see object_t.

Default type

With the default values for StringType (`std::string`), the default value for string_t is:

    std::string

Encoding

Strings are stored in UTF-8 encoding. Therefore, functions like `std::string::size()` or `std::string::length()` return the number of bytes in the string rather than the number of characters or glyphs.

String comparison

RFC 8259 states:

> Software implementations are typically required to test names of object members for equality. Implementations that transform the textual representation into sequences of Unicode code units and then perform the comparison numerically, code unit by code unit, are interoperable in the sense that implementations will agree in all cases on equality or inequality of two strings. For example, implementations that compare strings with escaped characters unconverted may incorrectly find that `"a\\b"` and `"a\u005Cb"` are not equal.

This implementation is interoperable as it does compare strings code unit by code unit.

Storage

String values are stored as pointers in a basic_json type. That is, for any access to string values, a pointer of type `string_t*` must be dereferenced.

version 1.0.0

BooleanType using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::boolean_t = BooleanType boolean_t

a type for a boolean

RFC 8259 implicitly describes a boolean as a type which differentiates the two literals `true` and `false`.

To store objects in C++, a type is defined by the template parameter BooleanType which chooses the type to use.

Default type

With the default values for BooleanType (`bool`), the default value for boolean_t is:

    bool

Storage

Boolean values are stored directly inside a basic_json type.

version 1.0.0

NumberIntegerType using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::number_integer_t = NumberIntegerType number_integer_t

a type for a number (integer)

RFC 8259 describes numbers as follows:

> The representation of numbers is similar to that used in most programming languages. A number is represented in base 10 using decimal digits. It contains an integer component that may be prefixed with an optional minus sign, which may be followed by a fraction part and/or an exponent part. Leading zeros are not allowed. (...) Numeric values that cannot be represented in the grammar below (such as Infinity and NaN) are not permitted.

This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, number_integer_t, number_unsigned_t and number_float_t are used.

To store integer numbers in C++, a type is defined by the template parameter NumberIntegerType which chooses the type to use.

Default type

With the default values for NumberIntegerType (`int64_t`), the default value for number_integer_t is:

    int64_t

Default behavior

- The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in integer literals lead to an interpretation as octal number. Internally, the value will be stored as decimal number. For instance, the C++ integer literal `010` will be serialized to `8`. During deserialization, leading zeros yield an error.

- Not-a-number (NaN) values will be serialized to `null`.

Limits

RFC 8259 specifies:

> An implementation may set limits on the range and precision of numbers.

When the default type is used, the maximal integer number that can be stored is `9223372036854775807` (INT64_MAX) and the minimal integer number that can be stored is `-9223372036854775808` (INT64_MIN). Integer numbers that are out of range will yield over/underflow when used in a constructor. During deserialization, too large or small integer numbers will be automatically be stored as number_unsigned_t or number_float_t.

RFC 8259 further states:

> Note that when such software is used, numbers that are integers and are in the range $[-2^{53}+1, 2^{53}-1]$ are interoperable in the sense that implementations will agree exactly on their numeric values.

As this range is a subrange of the exactly supported range [INT64_MIN, INT64_MAX], this class's integer type is interoperable.

Storage

Integer number values are stored directly inside a basic_json type.

see number_float_t type for number values (floating-point)

see number_unsigned_t type for number values (unsigned integer)

version 1.0.0

NumberUnsignedType using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::number_unsigned_t = NumberUnsignedType number_unsigned_t

a type for a number (unsigned)

RFC 8259 describes numbers as follows:

> The representation of numbers is similar to that used in most programming languages. A number is represented in base 10 using decimal digits. It contains an integer component that may be prefixed with an optional minus sign, which may be followed by a fraction part and/or an exponent part. Leading zeros are not allowed. (...) Numeric values that cannot be represented in the grammar below (such as Infinity and NaN) are not permitted.

This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, number_integer_t, number_unsigned_t and number_float_t are used.

To store unsigned integer numbers in C++, a type is defined by the template parameter NumberUnsignedType which chooses the type to use.

Default type

With the default values for NumberUnsignedType (`uint64_t`), the default value for number_unsigned_t is:

    uint64_t

Default behavior

- The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in integer literals lead to an interpretation as octal number. Internally, the value will be stored as decimal number. For instance, the C++ integer literal `010` will be serialized to `8`. During deserialization, leading zeros yield an error.

- Not-a-number (NaN) values will be serialized to `null`.

Limits

RFC 8259 specifies:

> An implementation may set limits on the range and precision of numbers.

When the default type is used, the maximal integer number that can be stored is `18446744073709551615` (UINT64_MAX) and the minimal integer number that can be stored is `0`. Integer numbers that are out of range will yield over/underflow when used in a constructor. During deserialization, too large or small integer numbers will be automatically be stored as number_integer_t or number_float_t.

RFC 8259 further states:

> Note that when such software is used, numbers that are integers and are in the range $[-2^{53}+1, 2^{53}-1]$ are interoperable in the sense that implementations will agree exactly on their numeric values.

As this range is a subrange (when considered in conjunction with the number_integer_t type) of the exactly supported range [0, UINT64_MAX], this class's integer type is interoperable.

Storage

Integer number values are stored directly inside a basic_json type.

see number_float_t type for number values (floating-point)

see number_integer_t type for number values (integer)

version 2.0.0

NumberFloatType using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::number_float_t = NumberFloatType number_float_t

a type for a number (floating-point)

RFC 8259 describes numbers as follows:

> The representation of numbers is similar to that used in most programming languages. A number is represented in base 10 using decimal digits. It contains an integer component that may be prefixed with an optional minus sign, which may be followed by a fraction part and/or an exponent part. Leading zeros are not allowed. (...) Numeric values that cannot be represented in the grammar below (such as Infinity and NaN) are not permitted.

This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, number_integer_t, number_unsigned_t and number_float_t are used.

To store floating-point numbers in C++, a type is defined by the template parameter NumberFloatType which chooses the type to use.

Default type

With the default values for NumberFloatType (`double`), the default value for number_float_t is:

    double

Default behavior

- The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in floating-point literals will be ignored. Internally, the value will be stored as decimal number. For instance, the C++ floating-point literal `01.2` will be serialized to `1.2`. During deserialization, leading zeros yield an error.

- Not-a-number (NaN) values will be serialized to `null`.

Limits

RFC 8259 states:

> This specification allows implementations to set limits on the range and precision of numbers accepted. Since software that implements IEEE 754-2008 binary64 (double precision) numbers is generally available and widely used, good interoperability can be achieved by implementations that expect no more precision or range than these provide, in the sense that implementations will approximate JSON numbers within the expected precision.

This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note values smaller than `-1.79769313486232e+308` and values greater than `1.79769313486232e+308` will be stored as NaN internally and be serialized to `null`.

Storage

Floating-point number values are stored directly inside a basic_json type.

see number_integer_t type for number values (integer)

see number_unsigned_t type for number values (unsigned integer)

version 1.0.0

nlohmann::byte_container_with_subtype< BinaryType > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::binary_t = nlohmann::byte_container_with_subtype<BinaryType> binary_t

a type for a packed binary type

This type is a type designed to carry binary data that appears in various serialized formats, such as CBOR's Major Type 2, MessagePack's bin, and BSON's generic binary subtype. This type is NOT a part of standard JSON and exists solely for compatibility with these binary types. As such, it is simply defined as an ordered sequence of zero or more byte values.

Additionally, as an implementation detail, the subtype of the binary data is carried around as a `std::uint8_t`, which is compatible with both of the binary data formats that use binary subtyping, (though the specific numbering is incompatible with each other, and it is up to the user to translate between them).

CBOR's RFC 7049 describes this type as:

> Major type 2: a byte string. The string's length in bytes is represented following the rules for positive integers (major type 0).

MessagePack's documentation on the bin type family describes this type as:

> Bin format family stores an byte array in 2, 3, or 5 bytes of extra bytes in addition to the size of the byte array.

BSON's specifications describe several binary types; however, this type is intended to represent the generic binary type which has the description:

> Generic binary subtype - This is the most commonly used binary subtype and should be the 'default' for drivers and tools.

None of these impose any limitations on the internal representation other than the basic unit of storage be some type of array whose parts are decomposable into bytes.

The default representation of this binary format is a `std::vector<std::uint8_t>`, which is a very common way to represent a byte array in modern C++.

Default type

The default values for BinaryType is `std::vector<std::uint8_t>`

Storage

Binary Arrays are stored as pointers in a basic_json type. That is, for any access to array values, a pointer of the type `binary_t*` must be dereferenced.

Notes on subtypes

- CBOR

  - Binary values are represented as byte strings. No subtypes are supported and will be ignored when CBOR is written.

- MessagePack

  - If a subtype is given and the binary array contains exactly 1, 2, 4, 8, or 16 elements, the fixext family (fixext1, fixext2, fixext4, fixext8) is used. For other sizes, the ext family (ext8, ext16, ext32) is used. The subtype is then added as singed 8-bit integer.

  - If no subtype is given, the bin family (bin8, bin16, bin32) is used.

- BSON

  - If a subtype is given, it is used and added as unsigned 8-bit integer.

  - If no subtype is given, the generic binary subtype 0x00 is used.

see binary create a binary array

version 3.8.0

constructors and destructors

Constructors of class basic_json, copy/move constructor, copy assignment, static functions creating objects, and the destructor.

JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::binary (const typename binary_t::container_type &init) binary const typename binary_t::container_type & init

explicitly create a binary array (without subtype)

Creates a JSON binary array value from a given binary container. Binary values are part of various binary formats, such as CBOR, MessagePack, and BSON. This constructor is used to create a value for serialization to those formats.

Note, this function exists because of the difficulty in correctly specifying the correct template overload in the standard value ctor, as both JSON arrays and JSON binary arrays are backed with some form of a `std::vector`. Because JSON binary arrays are a non-standard extension it was decided that it would be best to prevent automatic initialization of a binary array type, for backwards compatibility and so it does not happen on accident.

init

container containing bytes to use as binary type

JSON binary array value

Linear in the size of init.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

version 3.8.0

nlohmann::detail::binary
JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::binary (const typename binary_t::container_type &init, std::uint8_t subtype) binary const typename binary_t::container_type & init std::uint8_t subtype

explicitly create a binary array (with subtype)

Creates a JSON binary array value from a given binary container. Binary values are part of various binary formats, such as CBOR, MessagePack, and BSON. This constructor is used to create a value for serialization to those formats.

Note, this function exists because of the difficulty in correctly specifying the correct template overload in the standard value ctor, as both JSON arrays and JSON binary arrays are backed with some form of a `std::vector`. Because JSON binary arrays are a non-standard extension it was decided that it would be best to prevent automatic initialization of a binary array type, for backwards compatibility and so it does not happen on accident.

init

container containing bytes to use as binary type

subtype

subtype to use in MessagePack and BSON

JSON binary array value

Linear in the size of init.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

version 3.8.0

nlohmann::detail::binary
JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::binary (typename binary_t::container_type &&init) binary typename binary_t::container_type && init

explicitly create a binary array (without subtype)

Creates a JSON binary array value from a given binary container. Binary values are part of various binary formats, such as CBOR, MessagePack, and BSON. This constructor is used to create a value for serialization to those formats.

Note, this function exists because of the difficulty in correctly specifying the correct template overload in the standard value ctor, as both JSON arrays and JSON binary arrays are backed with some form of a `std::vector`. Because JSON binary arrays are a non-standard extension it was decided that it would be best to prevent automatic initialization of a binary array type, for backwards compatibility and so it does not happen on accident.

init

container containing bytes to use as binary type

JSON binary array value

Linear in the size of init.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

version 3.8.0

nlohmann::detail::binary
JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::binary (typename binary_t::container_type &&init, std::uint8_t subtype) binary typename binary_t::container_type && init std::uint8_t subtype

explicitly create a binary array (with subtype)

Creates a JSON binary array value from a given binary container. Binary values are part of various binary formats, such as CBOR, MessagePack, and BSON. This constructor is used to create a value for serialization to those formats.

Note, this function exists because of the difficulty in correctly specifying the correct template overload in the standard value ctor, as both JSON arrays and JSON binary arrays are backed with some form of a `std::vector`. Because JSON binary arrays are a non-standard extension it was decided that it would be best to prevent automatic initialization of a binary array type, for backwards compatibility and so it does not happen on accident.

init

container containing bytes to use as binary type

subtype

subtype to use in MessagePack and BSON

JSON binary array value

Linear in the size of init.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

version 3.8.0

nlohmann::detail::binary
JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::array (initializer_list_t init={}) array initializer_list_t init {}

explicitly create an array from an initializer list

Creates a JSON array value from a given initializer list. That is, given a list of values `a, b, c`, creates the JSON value `[a, b, c]`. If the initializer list is empty, the empty array `[]` is created.

This function is only needed to express two edge cases that cannot be realized with the initializer list constructor (basic_json(initializer_list_t, bool, value_t)). These cases are:

1. creating an array whose elements are all pairs whose first element is a string in this case, the initializer list constructor would create an object, taking the first elements as keys

2. creating an empty array passing the empty initializer list to the initializer list constructor yields an empty object

init

initializer list with JSON values to create an array from (optional)

JSON array value

Linear in the size of init.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

{The following code shows an example for the `array` function.,array}

see basic_json(initializer_list_t, bool, value_t) create a JSON value from an initializer list

see object(initializer_list_t) create a JSON object value from an initializer list

version 1.0.0

nlohmann::detail::array
JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::object (initializer_list_t init={}) object initializer_list_t init {}

explicitly create an object from an initializer list

Creates a JSON object value from a given initializer list. The initializer lists elements must be pairs, and their first elements must be strings. If the initializer list is empty, the empty object `{}` is created.

This function is only added for symmetry reasons. In contrast to the related function array(initializer_list_t), there are no cases which can only be expressed by this function. That is, any initializer list init can also be passed to the initializer list constructor basic_json(initializer_list_t, bool, value_t).

init

initializer list to create an object from (optional)

JSON object value

type_error.301

if init is not a list of pairs whose first elements are strings. In this case, no object can be created. When such a value is passed to basic_json(initializer_list_t, bool, value_t), an array would have been created from the passed initializer list init. See example below.

Linear in the size of init.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

{The following code shows an example for the `object` function.,object}

see basic_json(initializer_list_t, bool, value_t) create a JSON value from an initializer list

see array(initializer_list_t) create a JSON array value from an initializer list

version 1.0.0

nlohmann::detail::object
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(const value_t v)
basic_json
const value_t v

create an empty value with a given type

Create an empty JSON value with a given type. The value will be default initialized with an empty value which depends on the type:

Value type | initial value
null | `null`
boolean | `false`
string | `""`
number | `0`
object | `{}`
array | `[]`
binary | empty array

v

the type of the value to create

Constant.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

{The following code shows the constructor for different value_t values,basic_json__value_t}

see clear() restores the postcondition of this constructor

version 1.0.0

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(std::nullptr_t=nullptr) noexcept
basic_json
std::nullptr_t nullptr

create a null object

Create a `null` JSON value. It either takes a null pointer as parameter (explicitly creating `null`) or no parameter (implicitly creating `null`). The passed null pointer itself is not read it is only used to choose the right constructor.

Constant.

No-throw guarantee: this constructor never throws exceptions.

{The following code shows the constructor with and without a null pointer parameter.,basic_json__nullptr_t}

version 1.0.0

typename CompatibleType
typename U detail::uncvref_t<CompatibleType>
detail::enable_if_t< !detail::is_basic_json< U >::value &&detail::is_compatible_type< basic_json_t, U >::value, int > 0
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(CompatibleType &&val) noexcept(noexcept(//NOLINT(bugprone-forwarding-reference-overload, bugprone-exception-escape) JSONSerializer< U >::to_json(std::declval< basic_json_t &>(), std::forward< CompatibleType >(val))))
basic_json
CompatibleType && val

create a JSON value

This is a "catch all" constructor for all compatible JSON types; that is, types for which a `to_json()` method exists. The constructor forwards the parameter val to that method (to `json_serializer<U>::to_json` method with `U = uncvref_t<CompatibleType>`, to be exact).

Template type CompatibleType includes, but is not limited to, the following types:

- arrays: array_t and all kinds of compatible containers such as `std::vector`, `std::deque`, `std::list`, `std::forward_list`, `std::array`, `std::valarray`, `std::set`, `std::unordered_set`, `std::multiset`, and `std::unordered_multiset` with a `value_type` from which a basic_json value can be constructed.

- objects: object_t and all kinds of compatible associative containers such as `std::map`, `std::unordered_map`, `std::multimap`, and `std::unordered_multimap` with a `key_type` compatible to string_t and a `value_type` from which a basic_json value can be constructed.

- strings: string_t, string literals, and all compatible string containers can be used.

- numbers: number_integer_t, number_unsigned_t, number_float_t, and all convertible number types such as `int`, `size_t`, `int64_t`, `float` or `double` can be used.

- boolean: boolean_t / `bool` can be used.

- binary: binary_t / `std::vector<uint8_t>` may be used, unfortunately because string literals cannot be distinguished from binary character arrays by the C++ type system, all types compatible with `const char*` will be directed to the string constructor instead. This is both for backwards compatibility, and due to the fact that a binary type is not a standard JSON type.

See the examples below.

CompatibleType

a type such that:

- CompatibleType is not derived from `std::istream`,

- CompatibleType is not basic_json (to avoid hijacking copy/move constructors),

- CompatibleType is not a different basic_json type (i.e. with different template arguments)

- CompatibleType is not a basic_json nested type (e.g., json_pointer, iterator, etc ...)

- `json_serializer<U>` has a `to_json(basic_json_t&, CompatibleType&&)` method

U

= `uncvref_t<CompatibleType>`

val

the value to be forwarded to the respective constructor

Usually linear in the size of the passed val, also depending on the implementation of the called `to_json()` method.

Depends on the called constructor. For types directly supported by the library (i.e., all types for which no `to_json()` function was provided), strong guarantee holds: if an exception is thrown, there are no changes to any JSON value.

{The following code shows the constructor with several compatible types.,basic_json__CompatibleType}

version 2.1.0

nlohmann::detail::to_json
typename BasicJsonType
detail::enable_if_t< detail::is_basic_json< BasicJsonType >::value &&!std::is_same< basic_json, BasicJsonType >::value, int > 0
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(const BasicJsonType &val)
basic_json
const BasicJsonType & val

create a JSON value from an existing one

This is a constructor for existing basic_json types. It does not hijack copy/move constructors, since the parameter has different template arguments than the current ones.

The constructor tries to convert the internal m_value of the parameter.

BasicJsonType

a type such that:

- BasicJsonType is a basic_json type.

- BasicJsonType has different template arguments than basic_json_t.

val

the basic_json value to be converted.

Usually linear in the size of the passed val, also depending on the implementation of the called `to_json()` method.

Depends on the called constructor. For types directly supported by the library (i.e., all types for which no `to_json()` function was provided), strong guarantee holds: if an exception is thrown, there are no changes to any JSON value.

version 3.2.0

nlohmann::detail::array
nlohmann::detail::binary
nlohmann::detail::boolean
nlohmann::detail::discarded
JSON_ASSERT
nlohmann::detail::null
nlohmann::detail::number_float
nlohmann::detail::number_integer
nlohmann::detail::number_unsigned
nlohmann::detail::object
nlohmann::detail::string
nlohmann::detail::to_json
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(initializer_list_t init, bool type_deduction=true, value_t manual_type=value_t::array)
basic_json
initializer_list_t init
bool type_deduction true
value_t manual_type value_t::array

create a container (array or object) from an initializer list

Creates a JSON value of type array or object from the passed initializer list init. In case type_deduction is `true` (default), the type of the JSON value to be created is deducted from the initializer list init according to the following rules:

1. If the list is empty, an empty JSON object value `{}` is created.

2. If the list consists of pairs whose first element is a string, a JSON object value is created where the first elements of the pairs are treated as keys and the second elements are as values.

3. In all other cases, an array is created.

The rules aim to create the best fit between a C++ initializer list and JSON values. The rationale is as follows:

1. The empty initializer list is written as `{}` which is exactly an empty JSON object.

2. C++ has no way of describing mapped types other than to list a list of pairs. As JSON requires that keys must be of type string, rule 2 is the weakest constraint one can pose on initializer lists to interpret them as an object.

3. In all other cases, the initializer list could not be interpreted as JSON object type, so interpreting it as JSON array type is safe.

With the rules described above, the following JSON values cannot be expressed by an initializer list:

- the empty array (`[]`): use array(initializer_list_t) with an empty initializer list in this case

- arrays whose elements satisfy rule 2: use array(initializer_list_t) with the same initializer list in this case

When used without parentheses around an empty initializer list, basic_json() is called instead of this function, yielding the JSON null value.

init

initializer list with JSON values

type_deduction

internal parameter; when set to `true`, the type of the JSON value is deducted from the initializer list init; when set to `false`, the type provided via manual_type is forced. This mode is used by the functions array(initializer_list_t) and object(initializer_list_t).

manual_type

internal parameter; when type_deduction is set to `false`, the created JSON value will use the provided type (only value_t::array and value_t::object are valid); when type_deduction is set to `true`, this parameter has no effect

type_error.301

if type_deduction is `false`, manual_type is `value_t::object`, but init contains an element which is not a pair whose first element is a string. In this case, the constructor could not create an object. If type_deduction would have be `true`, an array would have been created. See object(initializer_list_t) for an example.

Linear in the size of the initializer list init.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

{The example below shows how JSON values are created from initializer lists.,basic_json__list_init_t}

see array(initializer_list_t) create a JSON array value from an initializer list

see object(initializer_list_t) create a JSON object value from an initializer list

version 1.0.0

nlohmann::detail::array
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_THROW
nlohmann::detail::object
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(size_type cnt, const basic_json &val)
basic_json
size_type cnt
const basic_json & val

construct an array with count copies of given value

Constructs a JSON array value by creating cnt copies of a passed value. In case cnt is `0`, an empty array is created.

cnt

the number of JSON copies of val to create

val

the JSON value to copy

`std::distance(begin(),end()) == cnt` holds.

Linear in cnt.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

{The following code shows examples for the basic_json(size_type\, const basic_json&) constructor.,basic_json__size_type_basic_json}

version 1.0.0

class InputIT
typename std::enable_if< std::is_same< InputIT, typename basic_json_t::iterator >::value||std::is_same< InputIT, typename basic_json_t::const_iterator >::value, int >::type 0
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(InputIT first, InputIT last)
basic_json
InputIT first
InputIT last

construct a JSON container given an iterator range

Constructs the JSON value with the contents of the range `[first, last)`. The semantics depends on the different types a JSON value can have:

- In case of a null type, invalid_iterator.206 is thrown.

- In case of other primitive types (number, boolean, or string), first must be `begin()` and last must be `end()`. In this case, the value is copied. Otherwise, invalid_iterator.204 is thrown.

- In case of structured types (array, object), the constructor behaves as similar versions for `std::vector` or `std::map`; that is, a JSON array or object is constructed from the values in the range.

InputIT

an input iterator type (iterator or const_iterator)

first

begin of the range to copy from (included)

last

end of the range to copy from (excluded)

Iterators first and last must be initialized. This precondition is enforced with an assertion (see warning). If assertions are switched off, a violation of this precondition yields undefined behavior.

Range `[first, last)` is valid. Usually, this precondition cannot be checked efficiently. Only certain edge cases are detected; see the description of the exceptions below. A violation of this precondition yields undefined behavior.

A precondition is enforced with a runtime assertion that will result in calling `std::abort` if this precondition is not met. Assertions can be disabled by defining `NDEBUG` at compile time. See https://en.cppreference.com/w/cpp/error/assert for more information.

invalid_iterator.201

if iterators first and last are not compatible (i.e., do not belong to the same JSON value). In this case, the range `[first, last)` is undefined.

invalid_iterator.204

if iterators first and last belong to a primitive type (number, boolean, or string), but first does not point to the first element any more. In this case, the range `[first, last)` is undefined. See example code below.

invalid_iterator.206

if iterators first and last belong to a null value. In this case, the range `[first, last)` is undefined.

Linear in distance between first and last.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

{The example below shows several ways to create JSON values by specifying a subrange with iterators.,basic_json__InputIt_InputIt}

version 1.0.0

nlohmann::detail::array
nlohmann::detail::binary
nlohmann::detail::boolean
nlohmann::detail::invalid_iterator::create
JSON_ASSERT
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::number_float
nlohmann::detail::number_integer
nlohmann::detail::number_unsigned
nlohmann::detail::object
nlohmann::detail::string
nlohmann::detail::value
typename JsonRef
detail::enable_if_t< detail::conjunction< detail::is_json_ref< JsonRef >, std::is_same< typename JsonRef::value_type, basic_json >>::value, int > 0
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(const JsonRef &ref)
basic_json
const JsonRef & ref
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(const basic_json &other)
basic_json
const basic_json & other

copy constructor

Creates a copy of a given JSON value.

other

the JSON value to copy

`*this == other`

Linear in the size of other.

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is linear.

- As postcondition, it holds: `other == basic_json(other)`.

{The following code shows an example for the copy constructor.,basic_json__basic_json}

version 1.0.0

nlohmann::detail::array
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::assert_invariant
nlohmann::detail::binary
nlohmann::detail::boolean
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::m_value
nlohmann::detail::number_float
nlohmann::detail::number_integer
nlohmann::detail::number_unsigned
nlohmann::detail::object
nlohmann::detail::string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
(basic_json &&other) noexcept
basic_json
basic_json && other

move constructor

Move constructor. Constructs a JSON value with the contents of the given value other using move semantics. It "steals" the resources from other and leaves it as JSON null value.

other

value to move to this object

`*this` has the same value as other before the call.

other is a JSON null value.

Constant.

No-throw guarantee: this constructor never throws exceptions.

This function helps `basic_json` satisfying the MoveConstructible requirements.

{The code below shows the move constructor explicitly called via std::move.,basic_json__moveconstructor}

version 1.0.0

nlohmann::detail::null
basic_json & basic_json& nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator= (basic_json other) noexcept(std::is_nothrow_move_constructible< value_t >::value &&std::is_nothrow_move_assignable< value_t >::value &&std::is_nothrow_move_constructible< json_value >::value &&std::is_nothrow_move_assignable< json_value >::value) operator= basic_json other

copy assignment

Copy assignment operator. Copies a JSON value via the "copy and swap" strategy: It is expressed in terms of the copy constructor, destructor, and the `swap()` member function.

other

value to copy from

Linear.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is linear.

{The code below shows and example for the copy assignment. It creates a copy of value `a` which is then swapped with `b`. Finally\, the copy of `a` (which is the null value after the swap) is destroyed.,basic_json__copyassignment}

version 1.0.0

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::assert_invariant
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::~basic_json
() noexcept
~basic_json

destructor

Destroys the JSON value and frees all allocated memory.

Linear.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is linear.

- All stored elements are destroyed and all memory is freed.

version 1.0.0

object inspection

Functions to inspect the type of a JSON value.

string_t string_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::dump (const int indent=-1, const char indent_char=' ', const bool ensure_ascii=false, const error_handler_t error_handler=error_handler_t::strict) const dump const int indent -1 const char indent_char ' ' const bool ensure_ascii false const error_handler_t error_handler error_handler_t::strict

serialization

Serialization function for JSON values. The function tries to mimic Python's `json.dumps()` function, and currently supports its indent and ensure_ascii parameters.

indent

If indent is nonnegative, then array elements and object members will be pretty-printed with that indent level. An indent level of `0` will only insert newlines. `-1` (the default) selects the most compact representation.

indent_char

The character to use for indentation if indent is greater than `0`. The default is (space).

ensure_ascii

If ensure_ascii is true, all non-ASCII characters in the output are escaped with `\uXXXX` sequences, and the result consists of ASCII characters only.

error_handler

how to react on decoding errors; there are three possible values: `strict` (throws and exception in case a decoding error occurs; default), `replace` (replace invalid UTF-8 sequences with U+FFFD), and `ignore` (ignore invalid UTF-8 sequences during serialization; all bytes are copied to the output unchanged).

string containing the serialization of the JSON value

type_error.316

if a string stored inside the JSON value is not UTF-8 encoded and error_handler is set to strict

Binary values are serialized as object containing two keys:

- "bytes": an array of bytes as integers

- "subtype": the subtype as integer or "null" if the binary has no subtype

Linear.

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

{The following example shows the effect of different indent\, indent_char\, and ensure_ascii parameters to the result of the serialization.,dump}

https://docs.python.org/2/library/json.html#json.dump

version 1.0.0; indentation character indent_char, option ensure_ascii and exceptions added in version 3.0.0; error handlers added in version 3.4.0; serialization of binary values added in version 3.8.0.

constexpr value_t constexpr value_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::type () const noexcept type

return the type of the JSON value (explicit)

Return the type of the JSON value as a value from the value_t enumeration.

the type of the JSON value

Value type | return value
null | value_t::null
boolean | value_t::boolean
string | value_t::string
number (integer) | value_t::number_integer
number (unsigned integer) | value_t::number_unsigned
number (floating-point) | value_t::number_float
object | value_t::object
array | value_t::array
binary | value_t::binary
discarded | value_t::discarded

Constant.
No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `type()` for all JSON types.,type}

see operator value_t() return the type of the JSON value (implicit)

see type_name() return the type as string

version 1.0.0

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_primitive () const noexcept is_primitive

return whether type is primitive

This function returns true if and only if the JSON type is primitive (string, number, boolean, or null).

`true` if type is primitive (string, number, boolean, or null), `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_primitive()` for all JSON types.,is_primitive}

see is_structured() returns whether JSON value is structured

see is_null() returns whether JSON value is `null`

see is_string() returns whether JSON value is a string

see is_boolean() returns whether JSON value is a boolean

see is_number() returns whether JSON value is a number

see is_binary() returns whether JSON value is a binary array

version 1.0.0

constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_structured () const noexcept is_structured

return whether type is structured

This function returns true if and only if the JSON type is structured (array or object).

`true` if type is structured (array or object), `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_structured()` for all JSON types.,is_structured}

see is_primitive() returns whether value is primitive

see is_array() returns whether value is an array

see is_object() returns whether value is an object

version 1.0.0

constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_null () const noexcept is_null

return whether value is null

This function returns true if and only if the JSON value is null.

`true` if type is null, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_null()` for all JSON types.,is_null}

version 1.0.0

nlohmann::detail::null
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_boolean () const noexcept is_boolean

return whether value is a boolean

This function returns true if and only if the JSON value is a boolean.

`true` if type is boolean, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_boolean()` for all JSON types.,is_boolean}

version 1.0.0

nlohmann::detail::boolean
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_number () const noexcept is_number

return whether value is a number

This function returns true if and only if the JSON value is a number. This includes both integer (signed and unsigned) and floating-point values.

`true` if type is number (regardless whether integer, unsigned integer or floating-type), `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_number()` for all JSON types.,is_number}

see is_number_integer() check if value is an integer or unsigned integer number

see is_number_unsigned() check if value is an unsigned integer number

see is_number_float() check if value is a floating-point number

version 1.0.0

constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_number_integer () const noexcept is_number_integer

return whether value is an integer number

This function returns true if and only if the JSON value is a signed or unsigned integer number. This excludes floating-point values.

`true` if type is an integer or unsigned integer number, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_number_integer()` for all JSON types.,is_number_integer}

see is_number() check if value is a number

see is_number_unsigned() check if value is an unsigned integer number

see is_number_float() check if value is a floating-point number

version 1.0.0

nlohmann::detail::number_integer
nlohmann::detail::number_unsigned
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_number_unsigned () const noexcept is_number_unsigned

return whether value is an unsigned integer number

This function returns true if and only if the JSON value is an unsigned integer number. This excludes floating-point and signed integer values.

`true` if type is an unsigned integer number, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_number_unsigned()` for all JSON types.,is_number_unsigned}

see is_number() check if value is a number

see is_number_integer() check if value is an integer or unsigned integer number

see is_number_float() check if value is a floating-point number

version 2.0.0

nlohmann::detail::number_unsigned
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_number_float () const noexcept is_number_float

return whether value is a floating-point number

This function returns true if and only if the JSON value is a floating-point number. This excludes signed and unsigned integer values.

`true` if type is a floating-point number, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_number_float()` for all JSON types.,is_number_float}

see is_number() check if value is number

see is_number_integer() check if value is an integer number

see is_number_unsigned() check if value is an unsigned integer number

version 1.0.0

nlohmann::detail::number_float
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_object () const noexcept is_object

return whether value is an object

This function returns true if and only if the JSON value is an object.

`true` if type is object, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_object()` for all JSON types.,is_object}

version 1.0.0

nlohmann::detail::object
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::destroy
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::merge_patch
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::update
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_array () const noexcept is_array

return whether value is an array

This function returns true if and only if the JSON value is an array.

`true` if type is array, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_array()` for all JSON types.,is_array}

version 1.0.0

nlohmann::detail::array
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::destroy
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_string () const noexcept is_string

return whether value is a string

This function returns true if and only if the JSON value is a string.

`true` if type is string, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_string()` for all JSON types.,is_string}

version 1.0.0

nlohmann::detail::string
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_binary () const noexcept is_binary

return whether value is a binary array

This function returns true if and only if the JSON value is a binary array.

`true` if type is binary array, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_binary()` for all JSON types.,is_binary}

version 3.8.0

nlohmann::detail::binary
constexpr bool constexpr bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_discarded () const noexcept is_discarded

return whether value is discarded

This function returns true if and only if the JSON value was discarded during parsing with a callback function (see parser_callback_t).

This function will always be `false` for JSON values after parsing. That is, discarded values can only occur during parsing, but will be removed when inside a structured value or replaced by null in other cases.

`true` if type is discarded, `false` otherwise.

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies `is_discarded()` for all JSON types.,is_discarded}

version 1.0.0

nlohmann::detail::discarded
constexpr constexpr nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator value_t () const noexcept operator value_t

return the type of the JSON value (implicit)

Implicitly return the type of the JSON value as a value from the value_t enumeration.

the type of the JSON value

Constant.

No-throw guarantee: this member function never throws exceptions.

{The following code exemplifies the value_t operator for all JSON types.,operator__value_t}

see type() return the type of the JSON value (explicit)

see type_name() return the type as string

version 1.0.0

value access

Direct access to the stored value of a JSON value.

typename ValueType
detail::enable_if_t< detail::is_default_constructible< ValueType >::value &&detail::has_from_json< basic_json_t, ValueType >::value, int > 0
ValueType ValueType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl (detail::priority_tag< 0 >) const noexcept(noexcept(JSONSerializer< ValueType >::from_json(std::declval< const basic_json_t &>(), std::declval< ValueType &>()))) get_impl detail::priority_tag< 0 >

get a value (explicit)

Explicit type conversion between the JSON value and a compatible value which is CopyConstructible and DefaultConstructible. The value is converted by calling the json_serializer<ValueType> `from_json()` method.

The function is equivalent to executing

    ValueTyperet;
    JSONSerializer<ValueType>::from_json(*this,ret);
    returnret;

This overloads is chosen if:

- ValueType is not basic_json,

- json_serializer<ValueType> has a `from_json()` method of the form `void from_json(const basic_json&, ValueType&)`, and

- json_serializer<ValueType> does not have a `from_json()` method of the form `ValueType from_json(const basic_json&)`

ValueType

the returned value type

copy of the JSON value, converted to ValueType

what

json_serializer<ValueType> `from_json()` method throws

{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers\, (2) A JSON array can be converted to a standard `std::vector<short>`\, (3) A JSON object can be converted to C++ associative containers such as `std::unordered_map<std::string\, json>`.,get__ValueType_const}

version 2.1.0

nlohmann::detail::from_json
typename ValueType
detail::enable_if_t< detail::has_non_default_from_json< basic_json_t, ValueType >::value, int > 0
ValueType ValueType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl (detail::priority_tag< 1 >) const noexcept(noexcept(JSONSerializer< ValueType >::from_json(std::declval< const basic_json_t &>()))) get_impl detail::priority_tag< 1 >

get a value (explicit); special case

Explicit type conversion between the JSON value and a compatible value which is not CopyConstructible and not DefaultConstructible. The value is converted by calling the json_serializer<ValueType> `from_json()` method.

The function is equivalent to executing

    returnJSONSerializer<ValueType>::from_json(*this);

This overloads is chosen if:

- ValueType is not basic_json and

- json_serializer<ValueType> has a `from_json()` method of the form `ValueType from_json(const basic_json&)`

If json_serializer<ValueType> has both overloads of `from_json()`, this one is chosen.

ValueType

the returned value type

copy of the JSON value, converted to ValueType

what

json_serializer<ValueType> `from_json()` method throws

version 2.1.0

nlohmann::detail::from_json
typename BasicJsonType
detail::enable_if_t< detail::is_basic_json< BasicJsonType >::value, int > 0
BasicJsonType BasicJsonType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl (detail::priority_tag< 2 >) const get_impl detail::priority_tag< 2 >

get special-case overload

This overloads converts the current basic_json in a different basic_json type

BasicJsonType

== basic_json

a copy of *this, converted into BasicJsonType

Depending on the implementation of the called `from_json()` method.

version 3.2.0

typename BasicJsonType
detail::enable_if_t< std::is_same< BasicJsonType, basic_json_t >::value, int > 0
basic_json basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl (detail::priority_tag< 3 >) const get_impl detail::priority_tag< 3 >

get special-case overload

This overloads avoids a lot of template boilerplate, it can be seen as the identity method

BasicJsonType

== basic_json

a copy of *this

Constant.

version 2.1.0

typename PointerType
detail::enable_if_t< std::is_pointer< PointerType >::value, int > 0
constexpr auto constexpr auto nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl (detail::priority_tag< 4 >) const noexcept -> decltype(std::declval< const basic_json_t &>().template get_ptr< PointerType >()) get_impl detail::priority_tag< 4 >

get a pointer value (explicit)

get a pointer value (explicit) Explicit pointer access to the internally stored JSON value. No copies are made.

The pointer becomes invalid if the underlying JSON object changes.

PointerType

pointer type; must be a pointer to array_t, object_t, string_t, boolean_t, number_integer_t, number_unsigned_t, or number_float_t.

pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; `nullptr` otherwise

Constant.

{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `nullptr` is returned if the value and the requested pointer type does not match.,get__PointerType}

see get_ptr() for explicit pointer-member access

version 1.0.0

typename PointerType
typename std::enable_if< std::is_pointer< PointerType >::value, int >::type 0
auto auto nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_ptr () noexcept -> decltype(std::declval< basic_json_t &>().get_impl_ptr(std::declval< PointerType >())) get_ptr

get a pointer value (implicit)

Implicit pointer access to the internally stored JSON value. No copies are made.

Writing data to the pointee of the result yields an undefined state.

PointerType

pointer type; must be a pointer to array_t, object_t, string_t, boolean_t, number_integer_t, number_unsigned_t, or number_float_t. Enforced by a static assertion.

pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; `nullptr` otherwise

Constant.

{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `nullptr` is returned if the value and the requested pointer type does not match.,get_ptr}

version 1.0.0

nlohmann::detail::value
typename PointerType
typename std::enable_if< std::is_pointer< PointerType >::value &&std::is_const< typename std::remove_pointer< PointerType >::type >::value, int >::type 0
constexpr auto constexpr auto nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_ptr () const noexcept -> decltype(std::declval< const basic_json_t &>().get_impl_ptr(std::declval< PointerType >())) get_ptr

get a pointer value (implicit)

get a pointer value (implicit) Implicit pointer access to the internally stored JSON value. No copies are made.

Writing data to the pointee of the result yields an undefined state.

PointerType

pointer type; must be a pointer to array_t, object_t, string_t, boolean_t, number_integer_t, number_unsigned_t, or number_float_t. Enforced by a static assertion.

pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; `nullptr` otherwise

Constant.

{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `nullptr` is returned if the value and the requested pointer type does not match.,get_ptr}

version 1.0.0

typename ValueTypeCV
typename ValueType detail::uncvref_t<ValueTypeCV>
auto auto nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get () const noexcept(noexcept(std::declval< const basic_json_t &>().template get_impl< ValueType >(detail::priority_tag< 4 > {}))) -> decltype(std::declval< const basic_json_t &>().template get_impl< ValueType >(detail::priority_tag< 4 > get

get a (pointer) value (explicit)

Performs explicit type conversion between the JSON value and a compatible value if required.

- If the requested type is a pointer to the internally stored JSON value that pointer is returned. No copies are made.

- If the requested type is the current basic_json, or a different basic_json convertible from the current basic_json.

- Otherwise the value is converted by calling the json_serializer<ValueType> `from_json()` method.

ValueTypeCV

the provided value type

ValueType

the returned value type

copy of the JSON value, converted to

ValueType

if necessary

what

json_serializer<ValueType> `from_json()` method throws if conversion is required

version 2.1.0

return return nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl (detail::priority_tag< 4 > {}) get_impl detail::priority_tag< 4 > {}
typename PointerType
typename std::enable_if< std::is_pointer< PointerType >::value, int >::type 0
auto auto nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get () noexcept -> decltype(std::declval< basic_json_t &>().template get_ptr< PointerType >()) get

get a pointer value (explicit)

Explicit pointer access to the internally stored JSON value. No copies are made.

The pointer becomes invalid if the underlying JSON object changes.

PointerType

pointer type; must be a pointer to array_t, object_t, string_t, boolean_t, number_integer_t, number_unsigned_t, or number_float_t.

pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; `nullptr` otherwise

Constant.

{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `nullptr` is returned if the value and the requested pointer type does not match.,get__PointerType}

see get_ptr() for explicit pointer-member access

version 1.0.0

typename ValueType
detail::enable_if_t< !detail::is_basic_json< ValueType >::value &&detail::has_from_json< basic_json_t, ValueType >::value, int > 0
ValueType & ValueType& nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_to (ValueType &v) const noexcept(noexcept(JSONSerializer< ValueType >::from_json(std::declval< const basic_json_t &>(), v))) get_to ValueType & v

get a value (explicit)

Explicit type conversion between the JSON value and a compatible value. The value is filled into the input parameter by calling the json_serializer<ValueType> `from_json()` method.

The function is equivalent to executing

    ValueTypev;
    JSONSerializer<ValueType>::from_json(*this,v);

This overloads is chosen if:

- ValueType is not basic_json,

- json_serializer<ValueType> has a `from_json()` method of the form `void from_json(const basic_json&, ValueType&)`, and

ValueType

the input parameter type.

the input parameter, allowing chaining calls.

what

json_serializer<ValueType> `from_json()` method throws

{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers\, (2) A JSON array can be converted to a standard `std::vector<short>`\, (3) A JSON object can be converted to C++ associative containers such as `std::unordered_map<std::string\, json>`.,get_to}

version 3.3.0

nlohmann::detail::from_json
typename ValueType
detail::enable_if_t< detail::is_basic_json< ValueType >::value, int > 0
ValueType & ValueType& nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_to (ValueType &v) const get_to ValueType & v
typename T
std::size_t N N
typename Array T (&)[N]
detail::enable_if_t< detail::has_from_json< basic_json_t, Array >::value, int > 0
Array Array nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_to (T(&v)[N]) const noexcept(noexcept(JSONSerializer< Array >::from_json(std::declval< const basic_json_t &>(), v))) get_to T(&) v [N] nlohmann::detail::from_json
typename ReferenceType
typename std::enable_if< std::is_reference< ReferenceType >::value, int >::type 0
ReferenceType ReferenceType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_ref () get_ref

get a reference value (implicit)

Implicit reference access to the internally stored JSON value. No copies are made.

Writing data to the referee of the result yields an undefined state.

ReferenceType

reference type; must be a reference to array_t, object_t, string_t, boolean_t, number_integer_t, or number_float_t. Enforced by static assertion.

reference to the internally stored JSON value if the requested reference type ReferenceType fits to the JSON value; throws type_error.303 otherwise

type_error.303

in case passed type ReferenceType is incompatible with the stored JSON value; see example below

Constant.

{The example shows several calls to `get_ref()`.,get_ref}

version 1.1.0

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::push_back
typename ReferenceType
typename std::enable_if< std::is_reference< ReferenceType >::value &&std::is_const< typename std::remove_reference< ReferenceType >::type >::value, int >::type 0
ReferenceType ReferenceType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_ref () const get_ref

get a reference value (implicit)

get a reference value (implicit) Implicit reference access to the internally stored JSON value. No copies are made.

Writing data to the referee of the result yields an undefined state.

ReferenceType

reference type; must be a reference to array_t, object_t, string_t, boolean_t, number_integer_t, or number_float_t. Enforced by static assertion.

reference to the internally stored JSON value if the requested reference type ReferenceType fits to the JSON value; throws type_error.303 otherwise

type_error.303

in case passed type ReferenceType is incompatible with the stored JSON value; see example below

Constant.

{The example shows several calls to `get_ref()`.,get_ref}

version 1.1.0

typename ValueType
typename std::enable_if< !std::is_pointer< ValueType >::value &&!std::is_same< ValueType, detail::json_ref< basic_json >>::value &&!std::is_same< ValueType, typename string_t::value_type >::value &&!detail::is_basic_json< ValueType >::value &&!std::is_same< ValueType, std::initializer_list< typename string_t::value_type >>::value &&detail::is_detected< detail::get_template_function, const basic_json_t &, ValueType >::value, int >::type 0
JSON_EXPLICIT JSON_EXPLICIT nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator ValueType () const operator ValueType

get a value (implicit)

Implicit type conversion between the JSON value and a compatible value. The call is realized by calling get() const.

ValueType

non-pointer type compatible to the JSON value, for instance `int` for JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for JSON arrays. The character type of string_t as well as an initializer list of this type is excluded to avoid ambiguities as these types implicitly convert to `std::string`.

copy of the JSON value, converted to type ValueType

type_error.302

in case passed type ValueType is incompatible to the JSON value type (e.g., the JSON value is of type boolean, but a string is requested); see example below

Linear in the size of the JSON value.

{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers\, (2) A JSON array can be converted to a standard `std::vector<short>`\, (3) A JSON object can be converted to C++ associative containers such as `std::unordered_map<std::string\, json>`.,operator__ValueType}

version 1.0.0

binary_t & binary_t& nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_binary () get_binary

reference to the binary value

type_error.302

if the value is not binary

see is_binary() to check if the value is binary

version 3.8.0

nlohmann::detail::type_error::create
JSON_THROW
nlohmann::detail::string
const binary_t & const binary_t& nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_binary () const get_binary

reference to the binary value

type_error.302

if the value is not binary

see is_binary() to check if the value is binary

version 3.8.0

nlohmann::detail::type_error::create
JSON_THROW
nlohmann::detail::string
element access

Access to the JSON value.

reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::at (size_type idx) at size_type idx

access specified array element with bounds checking

Returns a reference to the element at specified location idx, with bounds checking.

idx

index of the element to access

reference to the element at index idx

type_error.304

if the JSON value is not an array; in this case, calling `at` with an index makes no sense. See example below.

out_of_range.401

if the index idx is out of range of the array; that is, `idx >= size()`. See example below.

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Constant.

version 1.0.0

{The example below shows how array elements can be read and written using `at()`. It also demonstrates the different exceptions that can be thrown.,at__size_type}
nlohmann::detail::type_error::create
nlohmann::detail::out_of_range::create
JSON_CATCH
JSON_HEDLEY_LIKELY
JSON_THROW
JSON_TRY
nlohmann::detail::string
nlohmann::to_string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::at (size_type idx) const at size_type idx

access specified array element with bounds checking

Returns a const reference to the element at specified location idx, with bounds checking.

idx

index of the element to access

const reference to the element at index idx

type_error.304

if the JSON value is not an array; in this case, calling `at` with an index makes no sense. See example below.

out_of_range.401

if the index idx is out of range of the array; that is, `idx >= size()`. See example below.

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Constant.

version 1.0.0

{The example below shows how array elements can be read using `at()`. It also demonstrates the different exceptions that can be thrown., at__size_type_const}
nlohmann::detail::type_error::create
nlohmann::detail::out_of_range::create
JSON_CATCH
JSON_HEDLEY_LIKELY
JSON_THROW
JSON_TRY
nlohmann::detail::string
nlohmann::to_string
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::at (const typename object_t::key_type &key) at const typename object_t::key_type & key

access specified object element with bounds checking

Returns a reference to the element at with specified key key, with bounds checking.

key

key of the element to access

reference to the element at key key

type_error.304

if the JSON value is not an object; in this case, calling `at` with a key makes no sense. See example below.

out_of_range.403

if the key key is is not stored in the object; that is, `find(key) == end()`. See example below.

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Logarithmic in the size of the container.

see operator[](const typename object_t::key_type&) for unchecked access by reference

see value() for access by value with a default value

version 1.0.0

{The example below shows how object elements can be read and written using `at()`. It also demonstrates the different exceptions that can be thrown.,at__object_t_key_type}
nlohmann::detail::type_error::create
nlohmann::detail::out_of_range::create
JSON_CATCH
JSON_HEDLEY_LIKELY
JSON_THROW
JSON_TRY
nlohmann::detail::string
const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::at (const typename object_t::key_type &key) const at const typename object_t::key_type & key

access specified object element with bounds checking

Returns a const reference to the element at with specified key key, with bounds checking.

key

key of the element to access

const reference to the element at key key

type_error.304

if the JSON value is not an object; in this case, calling `at` with a key makes no sense. See example below.

out_of_range.403

if the key key is is not stored in the object; that is, `find(key) == end()`. See example below.

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Logarithmic in the size of the container.

see operator[](const typename object_t::key_type&) for unchecked access by reference

see value() for access by value with a default value

version 1.0.0

{The example below shows how object elements can be read using `at()`. It also demonstrates the different exceptions that can be thrown., at__object_t_key_type_const}
nlohmann::detail::type_error::create
nlohmann::detail::out_of_range::create
JSON_CATCH
JSON_HEDLEY_LIKELY
JSON_THROW
JSON_TRY
nlohmann::detail::string
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] (size_type idx) operator[] size_type idx

access specified array element

Returns a reference to the element at specified location idx.

If idx is beyond the range of the array (i.e., `idx >= size()`), then the array is silently filled up with `null` values to make `idx` a valid reference to the last stored element.

idx

index of the element to access

reference to the element at index idx

type_error.305

if the JSON value is not an array or null; in that cases, using the [] operator with an index makes no sense.

Constant if idx is in the range of the array. Otherwise linear in `idx - size()`.

{The example below shows how array elements can be read and written using `[]` operator. Note the addition of `null` values.,operatorarray__size_type}

version 1.0.0

nlohmann::detail::array
nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] (size_type idx) const operator[] size_type idx

access specified array element

Returns a const reference to the element at specified location idx.

idx

index of the element to access

const reference to the element at index idx

type_error.305

if the JSON value is not an array; in that case, using the [] operator with an index makes no sense.

Constant.

{The example below shows how array elements can be read using the `[]` operator.,operatorarray__size_type_const}

version 1.0.0

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::array
nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] (const typename object_t::key_type &key) operator[] const typename object_t::key_type & key

access specified object element

Returns a reference to the element at with specified key key.

If key is not found in the object, then it is silently added to the object and filled with a `null` value to make `key` a valid reference. In case the value was `null` before, it is converted to an object.

key

key of the element to access

reference to the element at key key

type_error.305

if the JSON value is not an object or null; in that cases, using the [] operator with a key makes no sense.

Logarithmic in the size of the container.

{The example below shows how object elements can be read and written using the `[]` operator.,operatorarray__key_type}

see at(const typename object_t::key_type&) for access by reference with range checking

see value() for access by value with a default value

version 1.0.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::object
nlohmann::detail::string
const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] (const typename object_t::key_type &key) const operator[] const typename object_t::key_type & key

read-only access specified object element

Returns a const reference to the element at with specified key key. No bounds checking is performed.

If the element with key key does not exist, the behavior is undefined.

key

key of the element to access

const reference to the element at key key

The element with key key must exist. This precondition is enforced with an assertion.

type_error.305

if the JSON value is not an object; in that case, using the [] operator with a key makes no sense.

Logarithmic in the size of the container.

{The example below shows how object elements can be read using the `[]` operator.,operatorarray__key_type_const}

see at(const typename object_t::key_type&) for access by reference with range checking

see value() for access by value with a default value

version 1.0.0

nlohmann::detail::type_error::create
JSON_ASSERT
JSON_HEDLEY_LIKELY
JSON_HEDLEY_NON_NULL
JSON_THROW
nlohmann::detail::string
typename T
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] (T *key) operator[] T * key

access specified object element

Returns a reference to the element at with specified key key.

If key is not found in the object, then it is silently added to the object and filled with a `null` value to make `key` a valid reference. In case the value was `null` before, it is converted to an object.

key

key of the element to access

reference to the element at key key

type_error.305

if the JSON value is not an object or null; in that cases, using the [] operator with a key makes no sense.

Logarithmic in the size of the container.

{The example below shows how object elements can be read and written using the `[]` operator.,operatorarray__key_type}

see at(const typename object_t::key_type&) for access by reference with range checking

see value() for access by value with a default value

version 1.1.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_HEDLEY_NON_NULL
JSON_THROW
nlohmann::detail::object
nlohmann::detail::string
typename T
const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] (T *key) const operator[] T * key

read-only access specified object element

Returns a const reference to the element at with specified key key. No bounds checking is performed.

If the element with key key does not exist, the behavior is undefined.

key

key of the element to access

const reference to the element at key key

The element with key key must exist. This precondition is enforced with an assertion.

type_error.305

if the JSON value is not an object; in that case, using the [] operator with a key makes no sense.

Logarithmic in the size of the container.

{The example below shows how object elements can be read using the `[]` operator.,operatorarray__key_type_const}

see at(const typename object_t::key_type&) for access by reference with range checking

see value() for access by value with a default value

version 1.1.0

nlohmann::detail::type_error::create
JSON_ASSERT
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
class ValueType
typename std::enable_if< detail::is_getable< basic_json_t, ValueType >::value &&!std::is_same< value_t, ValueType >::value, int >::type 0
ValueType ValueType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::value (const typename object_t::key_type &key, const ValueType &default_value) const value const typename object_t::key_type & key const ValueType & default_value

access specified object element with default value

Returns either a copy of an object's element at the specified key key or a given default value if no element with key key exists.

The function is basically equivalent to executing

    try{
    returnat(key);
    }catch(out_of_range){
    returndefault_value;
    }

Unlike at(const typename object_t::key_type&), this function does not throw if the given key key was not found.

Unlike operator[](const typename object_t::key_type& key), this function does not implicitly add an element to the position defined by key. This function is furthermore also applicable to const objects.

key

key of the element to access

default_value

the value to return if key is not found

ValueType

type compatible to JSON values, for instance `int` for JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for JSON arrays. Note the type of the expected value at key and the default value default_value must be compatible.

copy of the element at key key or default_value if key is not found

type_error.302

if default_value does not match the type of the value at key

type_error.306

if the JSON value is not an object; in that case, using `value()` with a key makes no sense.

Logarithmic in the size of the container.

{The example below shows how object elements can be queried with a default value.,basic_json__value}

see at(const typename object_t::key_type&) for access by reference with range checking

see operator[](const typename object_t::key_type&) for unchecked access by reference

version 1.0.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
string_t string_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::value (const typename object_t::key_type &key, const char *default_value) const value const typename object_t::key_type & key const char * default_value

overload for a default value of type const char*

access specified object element with default value Returns either a copy of an object's element at the specified key key or a given default value if no element with key key exists.

The function is basically equivalent to executing

    try{
    returnat(key);
    }catch(out_of_range){
    returndefault_value;
    }

Unlike at(const typename object_t::key_type&), this function does not throw if the given key key was not found.

Unlike operator[](const typename object_t::key_type& key), this function does not implicitly add an element to the position defined by key. This function is furthermore also applicable to const objects.

key

key of the element to access

default_value

the value to return if key is not found

ValueType

type compatible to JSON values, for instance `int` for JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for JSON arrays. Note the type of the expected value at key and the default value default_value must be compatible.

copy of the element at key key or default_value if key is not found

type_error.302

if default_value does not match the type of the value at key

type_error.306

if the JSON value is not an object; in that case, using `value()` with a key makes no sense.

Logarithmic in the size of the container.

{The example below shows how object elements can be queried with a default value.,basic_json__value}

see at(const typename object_t::key_type&) for access by reference with range checking

see operator[](const typename object_t::key_type&) for unchecked access by reference

version 1.0.0

nlohmann::detail::value
class ValueType
typename std::enable_if< detail::is_getable< basic_json_t, ValueType >::value, int >::type 0
ValueType ValueType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::value (const json_pointer &ptr, const ValueType &default_value) const value const json_pointer & ptr const ValueType & default_value

access specified object element via JSON Pointer with default value

Returns either a copy of an object's element at the specified key key or a given default value if no element with key key exists.

The function is basically equivalent to executing

    try{
    returnat(ptr);
    }catch(out_of_range){
    returndefault_value;
    }

Unlike at(const json_pointer&), this function does not throw if the given key key was not found.

ptr

a JSON pointer to the element to access

default_value

the value to return if ptr found no value

ValueType

type compatible to JSON values, for instance `int` for JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for JSON arrays. Note the type of the expected value at key and the default value default_value must be compatible.

copy of the element at key key or default_value if key is not found

type_error.302

if default_value does not match the type of the value at ptr

type_error.306

if the JSON value is not an object; in that case, using `value()` with a key makes no sense.

Logarithmic in the size of the container.

{The example below shows how object elements can be queried with a default value.,basic_json__value_ptr}

see operator[](const json_pointer&) for unchecked access by reference

version 2.0.2

nlohmann::detail::type_error::create
nlohmann::json_pointer< BasicJsonType >::get_checked
JSON_HEDLEY_LIKELY
JSON_HEDLEY_NON_NULL
JSON_INTERNAL_CATCH
JSON_THROW
JSON_TRY
nlohmann::detail::string
string_t string_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::value (const json_pointer &ptr, const char *default_value) const value const json_pointer & ptr const char * default_value

overload for a default value of type const char*

nlohmann::detail::value
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::front () front

access the first element

Returns a reference to the first element in the container. For a JSON container `c`, the expression `c.front()` is equivalent to `*c.begin()`.

In case of a structured type (array or object), a reference to the first element is returned. In case of number, string, boolean, or binary values, a reference to the value is returned.

Constant.

The JSON value must not be `null` (would throw `std::out_of_range`) or an empty array or object (undefined behavior, guarded by assertions).

The JSON value remains unchanged.

invalid_iterator.214

when called on `null` value

{The following code shows an example for `front()`.,front}

see back() access the last element

version 1.0.0

const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::front () const front

access the first element

Returns a reference to the first element in the container. For a JSON container `c`, the expression `c.front()` is equivalent to `*c.begin()`.

In case of a structured type (array or object), a reference to the first element is returned. In case of number, string, boolean, or binary values, a reference to the value is returned.

Constant.

The JSON value must not be `null` (would throw `std::out_of_range`) or an empty array or object (undefined behavior, guarded by assertions).

The JSON value remains unchanged.

invalid_iterator.214

when called on `null` value

{The following code shows an example for `front()`.,front}

see back() access the last element

version 1.0.0

reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::back () back

access the last element

Returns a reference to the last element in the container. For a JSON container `c`, the expression `c.back()` is equivalent to

    autotmp=c.end();
    --tmp;
    return*tmp;

In case of a structured type (array or object), a reference to the last element is returned. In case of number, string, boolean, or binary values, a reference to the value is returned.

Constant.

The JSON value must not be `null` (would throw `std::out_of_range`) or an empty array or object (undefined behavior, guarded by assertions).

The JSON value remains unchanged.

invalid_iterator.214

when called on a `null` value. See example below.

{The following code shows an example for `back()`.,back}

see front() access the first element

version 1.0.0

const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::back () const back

access the last element

Returns a reference to the last element in the container. For a JSON container `c`, the expression `c.back()` is equivalent to

    autotmp=c.end();
    --tmp;
    return*tmp;

In case of a structured type (array or object), a reference to the last element is returned. In case of number, string, boolean, or binary values, a reference to the value is returned.

Constant.

The JSON value must not be `null` (would throw `std::out_of_range`) or an empty array or object (undefined behavior, guarded by assertions).

The JSON value remains unchanged.

invalid_iterator.214

when called on a `null` value. See example below.

{The following code shows an example for `back()`.,back}

see front() access the first element

version 1.0.0

class IteratorType
typename std::enable_if< std::is_same< IteratorType, typename basic_json_t::iterator >::value||std::is_same< IteratorType, typename basic_json_t::const_iterator >::value, int >::type 0
IteratorType IteratorType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::erase (IteratorType pos) erase IteratorType pos

remove element given an iterator

Removes the element specified by iterator pos. The iterator pos must be valid and dereferenceable. Thus the `end()` iterator (which is valid, but is not dereferenceable) cannot be used as a value for pos.

If called on a primitive type other than `null`, the resulting JSON value will be `null`.

pos

iterator to the element to remove

Iterator following the last removed element. If the iterator pos refers to the last element, the `end()` iterator is returned.

IteratorType

an iterator or const_iterator

Invalidates iterators and references at or after the point of the erase, including the `end()` iterator.

type_error.307

if called on a `null` value; example: `"cannot use erase() with null"`

invalid_iterator.202

if called on an iterator which does not belong to the current JSON value; example: `"iterator does not fit current value"`

invalid_iterator.205

if called on a primitive type with invalid iterator (i.e., any iterator which is not `begin()`); example: `"iterator out of range"`

The complexity depends on the type:

- objects: amortized constant

- arrays: linear in distance between pos and the end of the container

- strings and binary: linear in the length of the member

- other types: constant

{The example shows the result of `erase()` for different JSON types.,erase__IteratorType}

see erase(IteratorType, IteratorType) removes the elements in the given range

see erase(const typename object_t::key_type&) removes the element from an object at the given key

see erase(const size_type) removes the element from an array at the given index

version 1.0.0

nlohmann::detail::array
nlohmann::detail::binary
nlohmann::detail::boolean
nlohmann::detail::invalid_iterator::create
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::null
nlohmann::detail::number_float
nlohmann::detail::number_integer
nlohmann::detail::number_unsigned
nlohmann::detail::object
nlohmann::detail::string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
class IteratorType
typename std::enable_if< std::is_same< IteratorType, typename basic_json_t::iterator >::value||std::is_same< IteratorType, typename basic_json_t::const_iterator >::value, int >::type 0
IteratorType IteratorType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::erase (IteratorType first, IteratorType last) erase IteratorType first IteratorType last

remove elements given an iterator range

Removes the element specified by the range `[first; last)`. The iterator first does not need to be dereferenceable if `first == last`: erasing an empty range is a no-op.

If called on a primitive type other than `null`, the resulting JSON value will be `null`.

first

iterator to the beginning of the range to remove

last

iterator past the end of the range to remove

Iterator following the last removed element. If the iterator second refers to the last element, the `end()` iterator is returned.

IteratorType

an iterator or const_iterator

Invalidates iterators and references at or after the point of the erase, including the `end()` iterator.

type_error.307

if called on a `null` value; example: `"cannot use erase() with null"`

invalid_iterator.203

if called on iterators which does not belong to the current JSON value; example: `"iterators do not fit current value"`

invalid_iterator.204

if called on a primitive type with invalid iterators (i.e., if `first != begin()` and `last != end()`); example: `"iterators out of range"`

The complexity depends on the type:

- objects: `log(size()) + std::distance(first, last)`

- arrays: linear in the distance between first and last, plus linear in the distance between last and end of the container

- strings and binary: linear in the length of the member

- other types: constant

{The example shows the result of `erase()` for different JSON types.,erase__IteratorType_IteratorType}

see erase(IteratorType) removes the element at a given position

see erase(const typename object_t::key_type&) removes the element from an object at the given key

see erase(const size_type) removes the element from an array at the given index

version 1.0.0

nlohmann::detail::array
nlohmann::detail::binary
nlohmann::detail::boolean
nlohmann::detail::invalid_iterator::create
nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::null
nlohmann::detail::number_float
nlohmann::detail::number_integer
nlohmann::detail::number_unsigned
nlohmann::detail::object
nlohmann::detail::string
size_type size_type nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::erase (const typename object_t::key_type &key) erase const typename object_t::key_type & key

remove element from a JSON object given a key

Removes elements from a JSON object with the key value key.

key

value of the elements to remove

Number of elements removed. If ObjectType is the default `std::map` type, the return value will always be `0` (key was not found) or `1` (key was found).

References and iterators to the erased elements are invalidated. Other references and iterators are not affected.

type_error.307

when called on a type other than JSON object; example: `"cannot use erase() with null"`

`log(size()) + count(key)`

{The example shows the effect of `erase()`.,erase__key_type}

see erase(IteratorType) removes the element at a given position

see erase(IteratorType, IteratorType) removes the elements in the given range

see erase(const size_type) removes the element from an array at the given index

version 1.0.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::erase (const size_type idx) erase const size_type idx

remove element from a JSON array given an index

Removes element from a JSON array at the index idx.

idx

index of the element to remove

type_error.307

when called on a type other than JSON object; example: `"cannot use erase() with null"`

out_of_range.401

when `idx >= size()`; example: `"array index 17 is out of range"`

Linear in distance between idx and the end of the container.

{The example shows the effect of `erase()`.,erase__size_type}

see erase(IteratorType) removes the element at a given position

see erase(IteratorType, IteratorType) removes the elements in the given range

see erase(const typename object_t::key_type&) removes the element from an object at the given key

version 1.0.0

nlohmann::detail::type_error::create
nlohmann::detail::out_of_range::create
JSON_HEDLEY_LIKELY
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::string
nlohmann::to_string
lookup
typename KeyT
iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::find (KeyT &&key) find KeyT && key

find an element in a JSON object

Finds an element in a JSON object with key equivalent to key. If the element is not found or the JSON value is not an object, end() is returned.

This method always returns end() when executed on a JSON type that is not an object.

key

key value of the element to search for.

Iterator to an element with key equivalent to key. If no such element is found or the JSON value is not an object, past-the-end (see end()) iterator is returned.

Logarithmic in the size of the JSON object.

{The example shows how `find()` is used.,find__key_type}

see contains(KeyT&&) const checks whether a key exists

version 1.0.0

nlohmann::detail::key
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
typename KeyT
const_iterator const_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::find (KeyT &&key) const find KeyT && key

find an element in a JSON object

find an element in a JSON object Finds an element in a JSON object with key equivalent to key. If the element is not found or the JSON value is not an object, end() is returned.

This method always returns end() when executed on a JSON type that is not an object.

key

key value of the element to search for.

Iterator to an element with key equivalent to key. If no such element is found or the JSON value is not an object, past-the-end (see end()) iterator is returned.

Logarithmic in the size of the JSON object.

{The example shows how `find()` is used.,find__key_type}

see contains(KeyT&&) const checks whether a key exists

version 1.0.0

nlohmann::detail::key
typename KeyT
size_type size_type nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::count (KeyT &&key) const count KeyT && key

returns the number of occurrences of a key in a JSON object

Returns the number of elements with key key. If ObjectType is the default `std::map` type, the return value will always be `0` (key was not found) or `1` (key was found).

This method always returns `0` when executed on a JSON type that is not an object.

key

key value of the element to count

Number of elements with key key. If the JSON value is not an object, the return value will be `0`.

Logarithmic in the size of the JSON object.

{The example shows how `count()` is used.,count}

version 1.0.0

nlohmann::detail::key
nlohmann::detail::value
typename KeyT
typename std::enable_if< !std::is_same< typename std::decay< KeyT >::type, json_pointer >::value, int >::type 0
bool bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::contains (KeyT &&key) const contains KeyT && key

check the existence of an element in a JSON object

Check whether an element exists in a JSON object with key equivalent to key. If the element is not found or the JSON value is not an object, false is returned.

This method always returns false when executed on a JSON type that is not an object.

key

key value to check its existence.

true if an element with specified key exists. If no such element with such key is found or the JSON value is not an object, false is returned.

Logarithmic in the size of the JSON object.

{The following code shows an example for `contains()`.,contains}

see find(KeyT&&) returns an iterator to an object element

see contains(const json_pointer&) const checks the existence for a JSON pointer

version 3.6.0

nlohmann::detail::key
cudnn_frontend::check_rule
bool bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::contains (const json_pointer &ptr) const contains const json_pointer & ptr

check the existence of an element in a JSON object given a JSON pointer

Check whether the given JSON pointer ptr can be resolved in the current JSON value.

This method can be executed on any JSON value type.

ptr

JSON pointer to check its existence.

true if the JSON pointer can be resolved to a stored value, false otherwise.

If `j.contains(ptr)` returns true, it is safe to call `j[ptr]`.

parse_error.106

if an array index begins with '0'

parse_error.109

if an array index was not a number

Logarithmic in the size of the JSON object.

{The following code shows an example for `contains()`.,contains_json_pointer}

see contains(KeyT &&) const checks the existence of a key

version 3.7.0

nlohmann::json_pointer< BasicJsonType >::contains
iterators
iteration_proxy< iterator > static iteration_proxy<iterator> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::iterator_wrapper (reference ref) noexcept iterator_wrapper reference ref

wrapper to access iterator member functions in range-based for

This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator.

For loop without iterator_wrapper:

    for(autoit=j_object.begin();it!=j_object.end();++it)
    {
    std::cout<<"key:"<<it.key()<<",value:"<<it.value()<<'\n';
    }

Range-based for loop without iterator proxy:

    for(autoit:j_object)
    {
    //"it"isoftypejson::referenceandhasnokey()member
    std::cout<<"value:"<<it<<'\n';
    }

Range-based for loop with iterator proxy:

    for(autoit:json::iterator_wrapper(j_object))
    {
    std::cout<<"key:"<<it.key()<<",value:"<<it.value()<<'\n';
    }

When iterating over an array, `key()` will return the index of the element as string (see example).

ref

reference to a JSON value

iteration proxy object wrapping ref with an interface to use in range-based for loops

{The following code shows how the wrapper is used,iterator_wrapper}

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Constant.

The name of this function is not yet final and may change in the future.

Deprecated

This stream operator is deprecated and will be removed in future 4.0.0 of the library. Please use items() instead; that is, replace `json::iterator_wrapper(j)` with `j.items()`.

JSON_HEDLEY_DEPRECATED_FOR
iteration_proxy< const_iterator > static iteration_proxy<const_iterator> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::iterator_wrapper (const_reference ref) noexcept iterator_wrapper const_reference ref

wrapper to access iterator member functions in range-based for

This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator.

For loop without iterator_wrapper:

    for(autoit=j_object.begin();it!=j_object.end();++it)
    {
    std::cout<<"key:"<<it.key()<<",value:"<<it.value()<<'\n';
    }

Range-based for loop without iterator proxy:

    for(autoit:j_object)
    {
    //"it"isoftypejson::referenceandhasnokey()member
    std::cout<<"value:"<<it<<'\n';
    }

Range-based for loop with iterator proxy:

    for(autoit:json::iterator_wrapper(j_object))
    {
    std::cout<<"key:"<<it.key()<<",value:"<<it.value()<<'\n';
    }

When iterating over an array, `key()` will return the index of the element as string (see example).

ref

reference to a JSON value

iteration proxy object wrapping ref with an interface to use in range-based for loops

{The following code shows how the wrapper is used,iterator_wrapper}

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Constant.

The name of this function is not yet final and may change in the future.

Deprecated

This stream operator is deprecated and will be removed in future 4.0.0 of the library. Please use items() instead; that is, replace `json::iterator_wrapper(j)` with `j.items()`.

iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::begin () noexcept begin

returns an iterator to the first element

Returns an iterator to the first element.

Illustration from cppreference.com

iterator to the first element

Constant.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

{The following code shows an example for `begin()`.,begin}

see cbegin() returns a const iterator to the beginning

see end() returns an iterator to the end

see cend() returns a const iterator to the end

version 1.0.0

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::merge_patch
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
const_iterator const_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::begin () const noexcept begin

returns a const iterator to the first element

Returns a const iterator to the first element.

Illustration from cppreference.com

const iterator to the first element

Constant.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

- Has the semantics of `const_cast<const basic_json&>(*this).begin()`.

{The following code shows an example for `cbegin()`.,cbegin}

see begin() returns an iterator to the beginning

see end() returns an iterator to the end

see cend() returns a const iterator to the end

version 1.0.0

const_iterator const_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::cbegin () const noexcept cbegin

returns a const iterator to the first element

Returns a const iterator to the first element.

Illustration from cppreference.com

const iterator to the first element

Constant.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

- Has the semantics of `const_cast<const basic_json&>(*this).begin()`.

{The following code shows an example for `cbegin()`.,cbegin}

see begin() returns an iterator to the beginning

see end() returns an iterator to the end

see cend() returns a const iterator to the end

version 1.0.0

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::update
iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::end () noexcept end

returns an iterator to one past the last element

Returns an iterator to one past the last element.

Illustration from cppreference.com

iterator one past the last element

Constant.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

{The following code shows an example for `end()`.,end}

see cend() returns a const iterator to the end

see begin() returns an iterator to the beginning

see cbegin() returns a const iterator to the beginning

version 1.0.0

nlohmann::detail::iter_impl< BasicJsonType >::set_end
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::merge_patch
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
const_iterator const_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::end () const noexcept end

returns a const iterator to one past the last element

Returns a const iterator to one past the last element.

Illustration from cppreference.com

const iterator one past the last element

Constant.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

- Has the semantics of `const_cast<const basic_json&>(*this).end()`.

{The following code shows an example for `cend()`.,cend}

see end() returns an iterator to the end

see begin() returns an iterator to the beginning

see cbegin() returns a const iterator to the beginning

version 1.0.0

const_iterator const_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::cend () const noexcept cend

returns a const iterator to one past the last element

Returns a const iterator to one past the last element.

Illustration from cppreference.com

const iterator one past the last element

Constant.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

- Has the semantics of `const_cast<const basic_json&>(*this).end()`.

{The following code shows an example for `cend()`.,cend}

see end() returns an iterator to the end

see begin() returns an iterator to the beginning

see cbegin() returns a const iterator to the beginning

version 1.0.0

nlohmann::detail::iter_impl< BasicJsonType >::set_end
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::update
reverse_iterator reverse_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::rbegin () noexcept rbegin

returns an iterator to the reverse-beginning

Returns an iterator to the reverse-beginning; that is, the last element.

Illustration from cppreference.com Constant.

This function helps `basic_json` satisfying the ReversibleContainer requirements:

- The complexity is constant.

- Has the semantics of `reverse_iterator(end())`.

{The following code shows an example for `rbegin()`.,rbegin}

see crbegin() returns a const reverse iterator to the beginning

see rend() returns a reverse iterator to the end

see crend() returns a const reverse iterator to the end

version 1.0.0

const_reverse_iterator const_reverse_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::rbegin () const noexcept rbegin

returns a const reverse iterator to the last element

Returns a const iterator to the reverse-beginning; that is, the last element.

Illustration from cppreference.com Constant.

This function helps `basic_json` satisfying the ReversibleContainer requirements:

- The complexity is constant.

- Has the semantics of `const_cast<const basic_json&>(*this).rbegin()`.

{The following code shows an example for `crbegin()`.,crbegin}

see rbegin() returns a reverse iterator to the beginning

see rend() returns a reverse iterator to the end

see crend() returns a const reverse iterator to the end

version 1.0.0

reverse_iterator reverse_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::rend () noexcept rend

returns an iterator to the reverse-end

Returns an iterator to the reverse-end; that is, one before the first element.

Illustration from cppreference.com Constant.

This function helps `basic_json` satisfying the ReversibleContainer requirements:

- The complexity is constant.

- Has the semantics of `reverse_iterator(begin())`.

{The following code shows an example for `rend()`.,rend}

see crend() returns a const reverse iterator to the end

see rbegin() returns a reverse iterator to the beginning

see crbegin() returns a const reverse iterator to the beginning

version 1.0.0

const_reverse_iterator const_reverse_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::rend () const noexcept rend

returns a const reverse iterator to one before the first

Returns a const reverse iterator to the reverse-end; that is, one before the first element.

Illustration from cppreference.com Constant.

This function helps `basic_json` satisfying the ReversibleContainer requirements:

- The complexity is constant.

- Has the semantics of `const_cast<const basic_json&>(*this).rend()`.

{The following code shows an example for `crend()`.,crend}

see rend() returns a reverse iterator to the end

see rbegin() returns a reverse iterator to the beginning

see crbegin() returns a const reverse iterator to the beginning

version 1.0.0

const_reverse_iterator const_reverse_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::crbegin () const noexcept crbegin

returns a const reverse iterator to the last element

Returns a const iterator to the reverse-beginning; that is, the last element.

Illustration from cppreference.com Constant.

This function helps `basic_json` satisfying the ReversibleContainer requirements:

- The complexity is constant.

- Has the semantics of `const_cast<const basic_json&>(*this).rbegin()`.

{The following code shows an example for `crbegin()`.,crbegin}

see rbegin() returns a reverse iterator to the beginning

see rend() returns a reverse iterator to the end

see crend() returns a const reverse iterator to the end

version 1.0.0

const_reverse_iterator const_reverse_iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::crend () const noexcept crend

returns a const reverse iterator to one before the first

Returns a const reverse iterator to the reverse-end; that is, one before the first element.

Illustration from cppreference.com Constant.

This function helps `basic_json` satisfying the ReversibleContainer requirements:

- The complexity is constant.

- Has the semantics of `const_cast<const basic_json&>(*this).rend()`.

{The following code shows an example for `crend()`.,crend}

see rend() returns a reverse iterator to the end

see rbegin() returns a reverse iterator to the beginning

see crbegin() returns a const reverse iterator to the beginning

version 1.0.0

JSON_HEDLEY_DEPRECATED_FOR
iteration_proxy< iterator > iteration_proxy<iterator> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::items () noexcept items

helper to access iterator member functions in range-based for

This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator.

For loop without `items()` function:

    for(autoit=j_object.begin();it!=j_object.end();++it)
    {
    std::cout<<"key:"<<it.key()<<",value:"<<it.value()<<'\n';
    }

Range-based for loop without `items()` function:

    for(autoit:j_object)
    {
    //"it"isoftypejson::referenceandhasnokey()member
    std::cout<<"value:"<<it<<'\n';
    }

Range-based for loop with `items()` function:

    for(auto&el:j_object.items())
    {
    std::cout<<"key:"<<el.key()<<",value:"<<el.value()<<'\n';
    }

The `items()` function also allows to use structured bindings (C++17):

    for(auto&[key,val]:j_object.items())
    {
    std::cout<<"key:"<<key<<",value:"<<val<<'\n';
    }

When iterating over an array, `key()` will return the index of the element as string (see example). For primitive types (e.g., numbers), `key()` returns an empty string.

Using `items()` on temporary objects is dangerous. Make sure the object's lifetime exeeds the iteration. See https://github.com/nlohmann/json/issues/2040 for more information.

iteration proxy object wrapping ref with an interface to use in range-based for loops

{The following code shows how the function is used.,items}

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Constant.

version 3.1.0, structured bindings support since 3.5.0.

iteration_proxy< const_iterator > iteration_proxy<const_iterator> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::items () const noexcept items

helper to access iterator member functions in range-based for

This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator.

For loop without `items()` function:

    for(autoit=j_object.begin();it!=j_object.end();++it)
    {
    std::cout<<"key:"<<it.key()<<",value:"<<it.value()<<'\n';
    }

Range-based for loop without `items()` function:

    for(autoit:j_object)
    {
    //"it"isoftypejson::referenceandhasnokey()member
    std::cout<<"value:"<<it<<'\n';
    }

Range-based for loop with `items()` function:

    for(auto&el:j_object.items())
    {
    std::cout<<"key:"<<el.key()<<",value:"<<el.value()<<'\n';
    }

The `items()` function also allows to use structured bindings (C++17):

    for(auto&[key,val]:j_object.items())
    {
    std::cout<<"key:"<<key<<",value:"<<val<<'\n';
    }

When iterating over an array, `key()` will return the index of the element as string (see example). For primitive types (e.g., numbers), `key()` returns an empty string.

Using `items()` on temporary objects is dangerous. Make sure the object's lifetime exeeds the iteration. See https://github.com/nlohmann/json/issues/2040 for more information.

iteration proxy object wrapping ref with an interface to use in range-based for loops

{The following code shows how the function is used.,items}

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Constant.

version 3.1.0, structured bindings support since 3.5.0.

capacity
bool bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::empty () const noexcept empty

checks whether the container is empty.

Checks if a JSON value has no elements (i.e. whether its size is `0`).

The return value depends on the different types and is defined as follows:

Value type | return value
null | `true`
boolean | `false`
string | `false`
number | `false`
binary | `false`
object | result of function `object_t::empty()`
array | result of function `array_t::empty()`

{The following code uses `empty()` to check if a JSON object contains any elements.,empty}
Constant, as long as array_t and object_t satisfy the Container concept; that is, their `empty()` functions have constant complexity.

No changes.

No-throw guarantee: this function never throws exceptions.

This function does not return whether a string stored as JSON value is empty - it returns whether the JSON container itself is empty which is false in the case of a string.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

- Has the semantics of `begin() == end()`.

see size() returns the number of elements

version 1.0.0

nlohmann::detail::array
nlohmann::detail::null
nlohmann::detail::object
size_type size_type nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::size () const noexcept size

returns the number of elements

Returns the number of elements in a JSON value.

The return value depends on the different types and is defined as follows:

Value type | return value
null | `0`
boolean | `1`
string | `1`
number | `1`
binary | `1`
object | result of function object_t::size()
array | result of function array_t::size()

{The following code calls `size()` on the different value types.,size}
Constant, as long as array_t and object_t satisfy the Container concept; that is, their size() functions have constant complexity.

No changes.

No-throw guarantee: this function never throws exceptions.

This function does not return the length of a string stored as JSON value - it returns the number of elements in the JSON value which is 1 in the case of a string.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

- Has the semantics of `std::distance(begin(), end())`.

see empty() checks whether the container is empty

see max_size() returns the maximal number of elements

version 1.0.0

nlohmann::detail::array
nlohmann::detail::null
nlohmann::detail::object
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
size_type size_type nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::max_size () const noexcept max_size

returns the maximum possible number of elements

Returns the maximum number of elements a JSON value is able to hold due to system or library implementation limitations, i.e. `std::distance(begin(), end())` for the JSON value.

The return value depends on the different types and is defined as follows:

Value type | return value
null | `0` (same as `size()`)
boolean | `1` (same as `size()`)
string | `1` (same as `size()`)
number | `1` (same as `size()`)
binary | `1` (same as `size()`)
object | result of function `object_t::max_size()`
array | result of function `array_t::max_size()`

{The following code calls `max_size()` on the different value types. Note the output is implementation specific.,max_size}
Constant, as long as array_t and object_t satisfy the Container concept; that is, their `max_size()` functions have constant complexity.

No changes.

No-throw guarantee: this function never throws exceptions.

This function helps `basic_json` satisfying the Container requirements:

- The complexity is constant.

- Has the semantics of returning `b.size()` where `b` is the largest possible JSON value.

see size() returns the number of elements

version 1.0.0

nlohmann::detail::array
nlohmann::detail::object
modifiers
friend void void swap (reference left, reference right) noexcept(std::is_nothrow_move_constructible< value_t >::value &&std::is_nothrow_move_assignable< value_t >::value &&std::is_nothrow_move_constructible< json_value >::value &&std::is_nothrow_move_assignable< json_value >::value) swap reference left reference right

exchanges the values

Exchanges the contents of the JSON value from left with those of right. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. implemented as a friend function callable via ADL.

left

JSON value to exchange the contents with

right

JSON value to exchange the contents with

Constant.

{The example below shows how JSON values can be swapped with `swap()`.,swap__reference}

version 1.0.0

void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::clear () noexcept clear

clears the contents

Clears the content of a JSON value and resets it to the default value as if basic_json(value_t) would have been called with the current value type from type():

Value type | initial value
null | `null`
boolean | `false`
string | `""`
number | `0`
binary | An empty byte vector
object | `{}`
array | `[]`

Has the same effect as calling

    *this=basic_json(type());

{The example below shows the effect of `clear()` to different JSON types.,clear}

Linear in the size of the JSON value.

All iterators, pointers and references related to this container are invalidated.

No-throw guarantee: this function never throws exceptions.

see basic_json(value_t) constructor that creates an object with the same value than calling `clear()`

version 1.0.0

nlohmann::detail::array
nlohmann::detail::binary
nlohmann::detail::boolean
nlohmann::detail::number_float
nlohmann::detail::number_integer
nlohmann::detail::number_unsigned
nlohmann::detail::object
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::push_back (basic_json &&val) push_back basic_json && val

add an object to an array

Appends the given element val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending val.

val

the value to add to the JSON array

type_error.308

when called on a type other than JSON array or null; example: `"cannot use push_back() with number"`

Amortized constant.

{The example shows how `push_back()` and `+=` can be used to add elements to a JSON array. Note how the `null` value was silently converted to a JSON array.,push_back}

version 1.0.0

nlohmann::detail::array
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator+= (basic_json &&val) operator+= basic_json && val

add an object to an array

add an object to an array Appends the given element val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending val.

val

the value to add to the JSON array

type_error.308

when called on a type other than JSON array or null; example: `"cannot use push_back() with number"`

Amortized constant.

{The example shows how `push_back()` and `+=` can be used to add elements to a JSON array. Note how the `null` value was silently converted to a JSON array.,push_back}

version 1.0.0

void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::push_back (const basic_json &val) push_back const basic_json & val

add an object to an array

add an object to an array Appends the given element val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending val.

val

the value to add to the JSON array

type_error.308

when called on a type other than JSON array or null; example: `"cannot use push_back() with number"`

Amortized constant.

{The example shows how `push_back()` and `+=` can be used to add elements to a JSON array. Note how the `null` value was silently converted to a JSON array.,push_back}

version 1.0.0

nlohmann::detail::array
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::string
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator+= (const basic_json &val) operator+= const basic_json & val

add an object to an array

add an object to an array Appends the given element val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending val.

val

the value to add to the JSON array

type_error.308

when called on a type other than JSON array or null; example: `"cannot use push_back() with number"`

Amortized constant.

{The example shows how `push_back()` and `+=` can be used to add elements to a JSON array. Note how the `null` value was silently converted to a JSON array.,push_back}

version 1.0.0

void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::push_back (const typename object_t::value_type &val) push_back const typename object_t::value_type & val

add an object to an object

Inserts the given element val to the JSON object. If the function is called on a JSON null value, an empty object is created before inserting val.

val

the value to add to the JSON object

type_error.308

when called on a type other than JSON object or null; example: `"cannot use push_back() with number"`

Logarithmic in the size of the container, O(log(`size()`)).

{The example shows how `push_back()` and `+=` can be used to add elements to a JSON object. Note how the `null` value was silently converted to a JSON object.,push_back__object_t__value}

version 1.0.0

nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::object
nlohmann::detail::string
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator+= (const typename object_t::value_type &val) operator+= const typename object_t::value_type & val

add an object to an object

add an object to an object Inserts the given element val to the JSON object. If the function is called on a JSON null value, an empty object is created before inserting val.

val

the value to add to the JSON object

type_error.308

when called on a type other than JSON object or null; example: `"cannot use push_back() with number"`

Logarithmic in the size of the container, O(log(`size()`)).

{The example shows how `push_back()` and `+=` can be used to add elements to a JSON object. Note how the `null` value was silently converted to a JSON object.,push_back__object_t__value}

version 1.0.0

void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::push_back (initializer_list_t init) push_back initializer_list_t init

add an object to an object

This function allows to use `push_back` with an initializer list. In case

1. the current value is an object,

2. the initializer list init contains only two elements, and

3. the first element of init is a string,

init is converted into an object element and added using push_back(const typename object_t::value_type&). Otherwise, init is converted to a JSON value and added using push_back(basic_json&&).

init

an initializer list

Linear in the size of the initializer list init.

This function is required to resolve an ambiguous overload error, because pairs like `{"key", "value"}` can be both interpreted as `object_t::value_type` or `std::initializer_list<basic_json>`, see https://github.com/nlohmann/json/issues/235 for more information.

{The example shows how initializer lists are treated as objects when possible.,push_back__initializer_list}
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_ref
nlohmann::detail::key
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator+= (initializer_list_t init) operator+= initializer_list_t init

add an object to an object

add an object to an object This function allows to use `push_back` with an initializer list. In case

1. the current value is an object,

2. the initializer list init contains only two elements, and

3. the first element of init is a string,

init is converted into an object element and added using push_back(const typename object_t::value_type&). Otherwise, init is converted to a JSON value and added using push_back(basic_json&&).

init

an initializer list

Linear in the size of the initializer list init.

This function is required to resolve an ambiguous overload error, because pairs like `{"key", "value"}` can be both interpreted as `object_t::value_type` or `std::initializer_list<basic_json>`, see https://github.com/nlohmann/json/issues/235 for more information.

{The example shows how initializer lists are treated as objects when possible.,push_back__initializer_list}
class... Args Args
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::emplace_back (Args &&... args) emplace_back Args &&... args

add an object to an array

Creates a JSON value from the passed parameters args to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending the value created from args.

args

arguments to forward to a constructor of basic_json

Args

compatible types to create a basic_json object

reference to the inserted element

type_error.311

when called on a type other than JSON array or null; example: `"cannot use emplace_back() with number"`

Amortized constant.

{The example shows how `push_back()` can be used to add elements to a JSON array. Note how the `null` value was silently converted to a JSON array.,emplace_back}

version 2.0.8, returns reference since 3.7.0

nlohmann::detail::array
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::string
class... Args Args
std::pair< iterator, bool > std::pair<iterator, bool> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::emplace (Args &&... args) emplace Args &&... args

add an object to an object if key does not exist

Inserts a new element into a JSON object constructed in-place with the given args if there is no element with the key in the container. If the function is called on a JSON null value, an empty object is created before appending the value created from args.

args

arguments to forward to a constructor of basic_json

Args

compatible types to create a basic_json object

a pair consisting of an iterator to the inserted element, or the already-existing element if no insertion happened, and a bool denoting whether the insertion took place.

type_error.311

when called on a type other than JSON object or null; example: `"cannot use emplace() with number"`

Logarithmic in the size of the container, O(log(`size()`)).

{The example shows how `emplace()` can be used to add elements to a JSON object. Note how the `null` value was silently converted to a JSON object. Further note how no value is added if there was already one value stored with the same key.,emplace}

version 2.0.8

nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::object
nlohmann::detail::string
typename... Args Args
iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert_iterator (const_iterator pos, Args &&... args) insert_iterator const_iterator pos Args &&... args

Helper for insertion of an iterator

: This uses std::distance to support GCC 4.8, see https://github.com/nlohmann/json/pull/1257

nlohmann::detail::internal_iterator< BasicJsonType >::array_iterator
JSON_ASSERT
nlohmann::detail::iter_impl< BasicJsonType >::m_it
iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert (const_iterator pos, const basic_json &val) insert const_iterator pos const basic_json & val

inserts element

Inserts element val before iterator pos.

pos

iterator before which the content will be inserted; may be the end() iterator

val

element to insert

iterator pointing to the inserted val.

type_error.309

if called on JSON values other than arrays; example: `"cannot use insert() with string"`

invalid_iterator.202

if pos is not an iterator of *this; example: `"iterator does not fit current value"`

Constant plus linear in the distance between pos and end of the container.

{The example shows how `insert()` is used.,insert}

version 1.0.0

nlohmann::detail::invalid_iterator::create
nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch
iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert (const_iterator pos, basic_json &&val) insert const_iterator pos basic_json && val

inserts element

inserts element Inserts element val before iterator pos.

pos

iterator before which the content will be inserted; may be the end() iterator

val

element to insert

iterator pointing to the inserted val.

type_error.309

if called on JSON values other than arrays; example: `"cannot use insert() with string"`

invalid_iterator.202

if pos is not an iterator of *this; example: `"iterator does not fit current value"`

Constant plus linear in the distance between pos and end of the container.

{The example shows how `insert()` is used.,insert}

version 1.0.0

iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert (const_iterator pos, size_type cnt, const basic_json &val) insert const_iterator pos size_type cnt const basic_json & val

inserts elements

Inserts cnt copies of val before iterator pos.

pos

iterator before which the content will be inserted; may be the end() iterator

cnt

number of copies of val to insert

val

element to insert

iterator pointing to the first element inserted, or pos if `cnt==0`

type_error.309

if called on JSON values other than arrays; example: `"cannot use insert() with string"`

invalid_iterator.202

if pos is not an iterator of *this; example: `"iterator does not fit current value"`

Linear in cnt plus linear in the distance between pos and end of the container.

{The example shows how `insert()` is used.,insert__count}

version 1.0.0

nlohmann::detail::invalid_iterator::create
nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::string
iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert (const_iterator pos, const_iterator first, const_iterator last) insert const_iterator pos const_iterator first const_iterator last

inserts elements

Inserts elements from range `[first, last)` before iterator pos.

pos

iterator before which the content will be inserted; may be the end() iterator

first

begin of the range of elements to insert

last

end of the range of elements to insert

type_error.309

if called on JSON values other than arrays; example: `"cannot use insert() with string"`

invalid_iterator.202

if pos is not an iterator of *this; example: `"iterator does not fit current value"`

invalid_iterator.210

if first and last do not belong to the same JSON value; example: `"iterators do not fit"`

invalid_iterator.211

if first or last are iterators into container for which insert is called; example: `"passed iterators may not belong to container"`

iterator pointing to the first element inserted, or pos if `first==last`

Linear in `std::distance(first, last)` plus linear in the distance between pos and end of the container.

{The example shows how `insert()` is used.,insert__range}

version 1.0.0

nlohmann::detail::internal_iterator< BasicJsonType >::array_iterator
nlohmann::detail::invalid_iterator::create
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::iter_impl< BasicJsonType >::m_it
nlohmann::detail::string
iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert (const_iterator pos, initializer_list_t ilist) insert const_iterator pos initializer_list_t ilist

inserts elements

Inserts elements from initializer list ilist before iterator pos.

pos

iterator before which the content will be inserted; may be the end() iterator

ilist

initializer list to insert the values from

type_error.309

if called on JSON values other than arrays; example: `"cannot use insert() with string"`

invalid_iterator.202

if pos is not an iterator of *this; example: `"iterator does not fit current value"`

iterator pointing to the first element inserted, or pos if `ilist` is empty

Linear in `ilist.size()` plus linear in the distance between pos and end of the container.

{The example shows how `insert()` is used.,insert__ilist}

version 1.0.0

nlohmann::detail::invalid_iterator::create
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert (const_iterator first, const_iterator last) insert const_iterator first const_iterator last

inserts elements

Inserts elements from range `[first, last)`.

first

begin of the range of elements to insert

last

end of the range of elements to insert

type_error.309

if called on JSON values other than objects; example: `"cannot use insert() with string"`

invalid_iterator.202

if iterator first or last does does not point to an object; example: `"iterators first and last must point to objects"`

invalid_iterator.210

if first and last do not belong to the same JSON value; example: `"iterators do not fit"`

Logarithmic: `O(N*log(size() + N))`, where `N` is the number of elements to insert.

{The example shows how `insert()` is used.,insert__range_object}

version 3.0.0

nlohmann::detail::invalid_iterator::create
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::iter_impl< BasicJsonType >::m_it
nlohmann::detail::internal_iterator< BasicJsonType >::object_iterator
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::update (const_reference j) update const_reference j

updates a JSON object from another object, overwriting existing keys

Inserts all values from JSON object j and overwrites existing keys.

j

JSON object to read values from

type_error.312

if called on JSON values other than objects; example: `"cannot use update() with string"`

O(N*log(size() + N)), where N is the number of elements to insert.

{The example shows how `update()` is used.,update}

https://docs.python.org/3.6/library/stdtypes.html#dict.update

version 3.0.0

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::cbegin
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::cend
nlohmann::detail::type_error::create
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_object
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::object
nlohmann::detail::string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::type_name
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::update (const_iterator first, const_iterator last) update const_iterator first const_iterator last

updates a JSON object from another object, overwriting existing keys

Inserts all values from from range `[first, last)` and overwrites existing keys.

first

begin of the range of elements to insert

last

end of the range of elements to insert

type_error.312

if called on JSON values other than objects; example: `"cannot use update() with string"`

invalid_iterator.202

if iterator first or last does does not point to an object; example: `"iterators first and last must point to objects"`

invalid_iterator.210

if first and last do not belong to the same JSON value; example: `"iterators do not fit"`

O(N*log(size() + N)), where N is the number of elements to insert.

{The example shows how `update()` is used__range.,update}

https://docs.python.org/3.6/library/stdtypes.html#dict.update

version 3.0.0

nlohmann::detail::invalid_iterator::create
nlohmann::detail::type_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::object
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::swap (reference other) noexcept(std::is_nothrow_move_constructible< value_t >::value &&std::is_nothrow_move_assignable< value_t >::value &&std::is_nothrow_move_constructible< json_value >::value &&std::is_nothrow_move_assignable< json_value >::value) swap reference other

exchanges the values

Exchanges the contents of the JSON value with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.

other

JSON value to exchange the contents with

Constant.

{The example below shows how JSON values can be swapped with `swap()`.,swap__reference}

version 1.0.0

void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::swap (array_t &other) swap array_t & other

exchanges the values

Exchanges the contents of a JSON array with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.

other

array to exchange the contents with

type_error.310

when JSON value is not an array; example: `"cannot use swap() with string"`

Constant.

{The example below shows how arrays can be swapped with `swap()`.,swap__array_t}

version 1.0.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::swap (object_t &other) swap object_t & other

exchanges the values

Exchanges the contents of a JSON object with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.

other

object to exchange the contents with

type_error.310

when JSON value is not an object; example: `"cannot use swap() with string"`

Constant.

{The example below shows how objects can be swapped with `swap()`.,swap__object_t}

version 1.0.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::swap (string_t &other) swap string_t & other

exchanges the values

Exchanges the contents of a JSON string with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.

other

string to exchange the contents with

type_error.310

when JSON value is not a string; example: `"cannot use swap() with boolean"`

Constant.

{The example below shows how strings can be swapped with `swap()`.,swap__string_t}

version 1.0.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::swap (binary_t &other) swap binary_t & other

exchanges the values

Exchanges the contents of a JSON string with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.

other

binary to exchange the contents with

type_error.310

when JSON value is not a string; example: `"cannot use swap() with boolean"`

Constant.

{The example below shows how strings can be swapped with `swap()`.,swap__binary_t}

version 3.8.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::swap (typename binary_t::container_type &other) swap typename binary_t::container_type & other

exchanges the values

Exchanges the contents of a JSON string with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.

other

binary to exchange the contents with

type_error.310

when JSON value is not a string; example: `"cannot use swap() with boolean"`

Constant.

{The example below shows how strings can be swapped with `swap()`.,swap__binary_t}

version 3.8.0

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
lexicographical comparison operators
friend bool bool operator== (const_reference lhs, const_reference rhs) noexcept operator== const_reference lhs const_reference rhs

comparison: equal

Compares two JSON values for equality according to the following rules:

- Two JSON values are equal if (1) they are from the same type and (2) their stored values are the same according to their respective `operator==`.

- Integer and floating-point numbers are automatically converted before comparison. Note that two NaN values are always treated as unequal.

- Two JSON null values are equal.

Floating-point inside JSON values numbers are compared with `json::number_float_t::operator==` which is `double::operator==` by default. To compare floating-point while respecting an epsilon, an alternative comparison function could be used, for instance

    template<typenameT,typename=typenamestd::enable_if<std::is_floating_point<T>::value,T>::type>
    inlineboolis_same(Ta,Tb,Tepsilon=std::numeric_limits<T>::epsilon())noexcept
    {
    returnstd::abs(a-b)<=epsilon;
    }

Or you can self-defined operator equal function like this:

    boolmy_equal(const_referencelhs,const_referencerhs){
    constautolhs_typelhs.type();
    constautorhs_typerhs.type();
    if(lhs_type==rhs_type){
    switch(lhs_type)
    //self_definedcase
    casevalue_t::number_float:
    returnstd::abs(lhs-rhs)<=std::numeric_limits<float>::epsilon();
    //othercasesremainthesamewiththeoriginal
    ...
    }
    ...
    }

NaN values never compare equal to themselves or to other NaN values.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether the values lhs and rhs are equal

No-throw guarantee: this function never throws exceptions.

Linear.

{The example demonstrates comparing several JSON types.,operator__equal}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator== (const_reference lhs, ScalarType rhs) noexcept operator== const_reference lhs ScalarType rhs

comparison: equal

comparison: equal Compares two JSON values for equality according to the following rules:

- Two JSON values are equal if (1) they are from the same type and (2) their stored values are the same according to their respective `operator==`.

- Integer and floating-point numbers are automatically converted before comparison. Note that two NaN values are always treated as unequal.

- Two JSON null values are equal.

Floating-point inside JSON values numbers are compared with `json::number_float_t::operator==` which is `double::operator==` by default. To compare floating-point while respecting an epsilon, an alternative comparison function could be used, for instance

    template<typenameT,typename=typenamestd::enable_if<std::is_floating_point<T>::value,T>::type>
    inlineboolis_same(Ta,Tb,Tepsilon=std::numeric_limits<T>::epsilon())noexcept
    {
    returnstd::abs(a-b)<=epsilon;
    }

Or you can self-defined operator equal function like this:

    boolmy_equal(const_referencelhs,const_referencerhs){
    constautolhs_typelhs.type();
    constautorhs_typerhs.type();
    if(lhs_type==rhs_type){
    switch(lhs_type)
    //self_definedcase
    casevalue_t::number_float:
    returnstd::abs(lhs-rhs)<=std::numeric_limits<float>::epsilon();
    //othercasesremainthesamewiththeoriginal
    ...
    }
    ...
    }

NaN values never compare equal to themselves or to other NaN values.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether the values lhs and rhs are equal

No-throw guarantee: this function never throws exceptions.

Linear.

{The example demonstrates comparing several JSON types.,operator__equal}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator== (ScalarType lhs, const_reference rhs) noexcept operator== ScalarType lhs const_reference rhs

comparison: equal

comparison: equal Compares two JSON values for equality according to the following rules:

- Two JSON values are equal if (1) they are from the same type and (2) their stored values are the same according to their respective `operator==`.

- Integer and floating-point numbers are automatically converted before comparison. Note that two NaN values are always treated as unequal.

- Two JSON null values are equal.

Floating-point inside JSON values numbers are compared with `json::number_float_t::operator==` which is `double::operator==` by default. To compare floating-point while respecting an epsilon, an alternative comparison function could be used, for instance

    template<typenameT,typename=typenamestd::enable_if<std::is_floating_point<T>::value,T>::type>
    inlineboolis_same(Ta,Tb,Tepsilon=std::numeric_limits<T>::epsilon())noexcept
    {
    returnstd::abs(a-b)<=epsilon;
    }

Or you can self-defined operator equal function like this:

    boolmy_equal(const_referencelhs,const_referencerhs){
    constautolhs_typelhs.type();
    constautorhs_typerhs.type();
    if(lhs_type==rhs_type){
    switch(lhs_type)
    //self_definedcase
    casevalue_t::number_float:
    returnstd::abs(lhs-rhs)<=std::numeric_limits<float>::epsilon();
    //othercasesremainthesamewiththeoriginal
    ...
    }
    ...
    }

NaN values never compare equal to themselves or to other NaN values.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether the values lhs and rhs are equal

No-throw guarantee: this function never throws exceptions.

Linear.

{The example demonstrates comparing several JSON types.,operator__equal}

version 1.0.0

friend bool bool operator!= (const_reference lhs, const_reference rhs) noexcept operator!= const_reference lhs const_reference rhs

comparison: not equal

Compares two JSON values for inequality by calculating `not (lhs == rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether the values lhs and rhs are not equal

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__notequal}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator!= (const_reference lhs, ScalarType rhs) noexcept operator!= const_reference lhs ScalarType rhs

comparison: not equal

comparison: not equal Compares two JSON values for inequality by calculating `not (lhs == rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether the values lhs and rhs are not equal

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__notequal}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator!= (ScalarType lhs, const_reference rhs) noexcept operator!= ScalarType lhs const_reference rhs

comparison: not equal

comparison: not equal Compares two JSON values for inequality by calculating `not (lhs == rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether the values lhs and rhs are not equal

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__notequal}

version 1.0.0

friend bool bool operator< (const_reference lhs, const_reference rhs) noexcept operator< const_reference lhs const_reference rhs

comparison: less than

Compares whether one JSON value lhs is less than another JSON value rhs according to the following rules:

- If lhs and rhs have the same type, the values are compared using the default `<` operator.

- Integer and floating-point numbers are automatically converted before comparison

- In case lhs and rhs have different types, the values are ignored and the order of the types is considered, see operator<(const value_t, const value_t).

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is less than rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__less}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator< (const_reference lhs, ScalarType rhs) noexcept operator< const_reference lhs ScalarType rhs

comparison: less than

comparison: less than Compares whether one JSON value lhs is less than another JSON value rhs according to the following rules:

- If lhs and rhs have the same type, the values are compared using the default `<` operator.

- Integer and floating-point numbers are automatically converted before comparison

- In case lhs and rhs have different types, the values are ignored and the order of the types is considered, see operator<(const value_t, const value_t).

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is less than rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__less}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator< (ScalarType lhs, const_reference rhs) noexcept operator< ScalarType lhs const_reference rhs

comparison: less than

comparison: less than Compares whether one JSON value lhs is less than another JSON value rhs according to the following rules:

- If lhs and rhs have the same type, the values are compared using the default `<` operator.

- Integer and floating-point numbers are automatically converted before comparison

- In case lhs and rhs have different types, the values are ignored and the order of the types is considered, see operator<(const value_t, const value_t).

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is less than rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__less}

version 1.0.0

friend bool bool operator<= (const_reference lhs, const_reference rhs) noexcept operator<= const_reference lhs const_reference rhs

comparison: less than or equal

Compares whether one JSON value lhs is less than or equal to another JSON value by calculating `not (rhs < lhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is less than or equal to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__greater}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator<= (const_reference lhs, ScalarType rhs) noexcept operator<= const_reference lhs ScalarType rhs

comparison: less than or equal

comparison: less than or equal Compares whether one JSON value lhs is less than or equal to another JSON value by calculating `not (rhs < lhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is less than or equal to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__greater}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator<= (ScalarType lhs, const_reference rhs) noexcept operator<= ScalarType lhs const_reference rhs

comparison: less than or equal

comparison: less than or equal Compares whether one JSON value lhs is less than or equal to another JSON value by calculating `not (rhs < lhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is less than or equal to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__greater}

version 1.0.0

friend bool bool operator> (const_reference lhs, const_reference rhs) noexcept operator> const_reference lhs const_reference rhs

comparison: greater than

Compares whether one JSON value lhs is greater than another JSON value by calculating `not (lhs <= rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is greater than to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__lessequal}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator> (const_reference lhs, ScalarType rhs) noexcept operator> const_reference lhs ScalarType rhs

comparison: greater than

comparison: greater than Compares whether one JSON value lhs is greater than another JSON value by calculating `not (lhs <= rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is greater than to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__lessequal}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator> (ScalarType lhs, const_reference rhs) noexcept operator> ScalarType lhs const_reference rhs

comparison: greater than

comparison: greater than Compares whether one JSON value lhs is greater than another JSON value by calculating `not (lhs <= rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is greater than to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__lessequal}

version 1.0.0

friend bool bool operator>= (const_reference lhs, const_reference rhs) noexcept operator>= const_reference lhs const_reference rhs

comparison: greater than or equal

Compares whether one JSON value lhs is greater than or equal to another JSON value by calculating `not (lhs < rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is greater than or equal to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__greaterequal}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator>= (const_reference lhs, ScalarType rhs) noexcept operator>= const_reference lhs ScalarType rhs

comparison: greater than or equal

comparison: greater than or equal Compares whether one JSON value lhs is greater than or equal to another JSON value by calculating `not (lhs < rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is greater than or equal to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__greaterequal}

version 1.0.0

typename ScalarType
typename std::enable_if< std::is_scalar< ScalarType >::value, int >::type 0
friend bool bool operator>= (ScalarType lhs, const_reference rhs) noexcept operator>= ScalarType lhs const_reference rhs

comparison: greater than or equal

comparison: greater than or equal Compares whether one JSON value lhs is greater than or equal to another JSON value by calculating `not (lhs < rhs)`.

lhs

first JSON value to consider

rhs

second JSON value to consider

whether lhs is greater than or equal to rhs

Linear.

No-throw guarantee: this function never throws exceptions.

{The example demonstrates comparing several JSON types.,operator__greaterequal}

version 1.0.0

serialization
friend std::ostream & std::ostream& operator<< (std::ostream &o, const basic_json &j) operator<< std::ostream & o const basic_json & j

serialize to stream

Serialize the given JSON value j to the output stream o. The JSON value will be serialized using the dump member function.

- The indentation of the output can be controlled with the member variable `width` of the output stream o. For instance, using the manipulator `std::setw(4)` on o sets the indentation level to `4` and the serialization result is the same as calling `dump(4)`.

- The indentation character can be controlled with the member variable `fill` of the output stream o. For instance, the manipulator `std::setfill('\t')` sets indentation to use a tab character rather than the default space character.

o

stream to serialize to

j

JSON value to serialize

the stream o

type_error.316

if a string stored inside the JSON value is not UTF-8 encoded

Linear.

{The example below shows the serialization with different parameters to `width` to adjust the indentation level.,operator_serialize}

version 1.0.0; indentation character added in version 3.0.0

friend std::ostream & std::ostream& operator>> (const basic_json &j, std::ostream &o) operator>> const basic_json & j std::ostream & o

serialize to stream

Deprecated

This stream operator is deprecated and will be removed in future 4.0.0 of the library. Please use operator<<(std::ostream&, const basic_json&) instead; that is, replace calls like `j >> o;` with `o << j;`.

version 1.0.0; deprecated since version 3.0.0

deserialization
friend std::istream & std::istream& operator<< (basic_json &j, std::istream &i) operator<< basic_json & j std::istream & i

deserialize from stream

Deprecated

This stream operator is deprecated and will be removed in version 4.0.0 of the library. Please use operator>>(std::istream&, basic_json&) instead; that is, replace calls like `j << i;` with `i >> j;`.

version 1.0.0; deprecated since version 3.0.0

friend std::istream & std::istream& operator>> (std::istream &i, basic_json &j) operator>> std::istream & i basic_json & j

deserialize from stream

Deserializes an input stream to a JSON value.

i

input stream to read a serialized JSON value from

j

JSON value to write the deserialized input to

parse_error.101

in case of an unexpected token

parse_error.102

if to_unicode fails or surrogate error

parse_error.103

if to_unicode fails

Linear in the length of the input. The parser is a predictive LL(1) parser.

A UTF-8 byte order mark is silently ignored.

{The example below shows how a JSON value is constructed by reading a serialization from a stream.,operator_deserialize}

parse(std::istream&, const parser_callback_t) for a variant with a parser callback function to filter values while parsing

version 1.0.0

typename InputType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parse (InputType &&i, const parser_callback_t cb=nullptr, const bool allow_exceptions=true, const bool ignore_comments=false) parse InputType && i const parser_callback_t cb nullptr const bool allow_exceptions true const bool ignore_comments false

deserialize from a compatible input

InputType

A compatible input, for instance

- an std::istream object

- a FILE pointer

- a C-style array of characters

- a pointer to a null-terminated string of single byte characters

- an object obj for which begin(obj) and end(obj) produces a valid pair of iterators.

i

input to read from

cb

a parser callback function of type parser_callback_t which is used to control the deserialization by filtering unwanted values (optional)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

ignore_comments

whether comments should be ignored and treated like whitespace (true) or yield a parse error (true); (optional, false by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.101

if a parse error occurs; example: `""unexpected end of input; expected string literal""`

parse_error.102

if to_unicode fails or surrogate error

parse_error.103

if to_unicode fails

Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the parser callback function cb or reading from the input i has a super-linear complexity.

A UTF-8 byte order mark is silently ignored.

{The example below demonstrates the `parse()` function reading from an array.,parse__array__parser_callback_t}

{The example below demonstrates the `parse()` function with and without callback function.,parse__string__parser_callback_t}

{The example below demonstrates the `parse()` function with and without callback function.,parse__istream__parser_callback_t}

{The example below demonstrates the `parse()` function reading from a contiguous container.,parse__contiguouscontainer__parser_callback_t}

version 2.0.3 (contiguous containers); version 3.9.0 allowed to ignore comments.

nlohmann::detail::input_adapter
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parse
operator"" _json
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parse
typename IteratorType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parse (IteratorType first, IteratorType last, const parser_callback_t cb=nullptr, const bool allow_exceptions=true, const bool ignore_comments=false) parse IteratorType first IteratorType last const parser_callback_t cb nullptr const bool allow_exceptions true const bool ignore_comments false

deserialize from a pair of character iterators

The value_type of the iterator must be a integral type with size of 1, 2 or 4 bytes, which will be interpreted respectively as UTF-8, UTF-16 and UTF-32.

first

iterator to start of character range

last

iterator to end of character range

cb

a parser callback function of type parser_callback_t which is used to control the deserialization by filtering unwanted values (optional)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

ignore_comments

whether comments should be ignored and treated like whitespace (true) or yield a parse error (true); (optional, false by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.101

if a parse error occurs; example: `""unexpected end of input; expected string literal""`

parse_error.102

if to_unicode fails or surrogate error

parse_error.103

if to_unicode fails

nlohmann::detail::input_adapter
JSON_HEDLEY_DEPRECATED_FOR
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parse
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parse (detail::span_input_adapter &&i, const parser_callback_t cb=nullptr, const bool allow_exceptions=true, const bool ignore_comments=false) parse detail::span_input_adapter && i const parser_callback_t cb nullptr const bool allow_exceptions true const bool ignore_comments false
typename InputType
bool static bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::accept (InputType &&i, const bool ignore_comments=false) accept InputType && i const bool ignore_comments false

check if the input is valid JSON

Unlike the parse(InputType&&, const parser_callback_t,const bool) function, this function neither throws an exception in case of invalid JSON input (i.e., a parse error) nor creates diagnostic information.

InputType

A compatible input, for instance

- an std::istream object

- a FILE pointer

- a C-style array of characters

- a pointer to a null-terminated string of single byte characters

- an object obj for which begin(obj) and end(obj) produces a valid pair of iterators.

i

input to read from

ignore_comments

whether comments should be ignored and treated like whitespace (true) or yield a parse error (true); (optional, false by default)

Whether the input read from i is valid JSON.

Linear in the length of the input. The parser is a predictive LL(1) parser.

A UTF-8 byte order mark is silently ignored.

{The example below demonstrates the `accept()` function reading from a string.,accept__string}
nlohmann::detail::input_adapter
typename IteratorType
bool static bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::accept (IteratorType first, IteratorType last, const bool ignore_comments=false) accept IteratorType first IteratorType last const bool ignore_comments false nlohmann::detail::input_adapter JSON_HEDLEY_DEPRECATED_FOR JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_HEDLEY_WARN_UNUSED_RESULT bool static JSON_HEDLEY_WARN_UNUSED_RESULT bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::accept (detail::span_input_adapter &&i, const bool ignore_comments=false) accept detail::span_input_adapter && i const bool ignore_comments false JSON_HEDLEY_NON_NULL
typename InputType
typename SAX
bool static bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::sax_parse (InputType &&i, SAX *sax, input_format_t format=input_format_t::json, const bool strict=true, const bool ignore_comments=false) sax_parse InputType && i SAX * sax input_format_t format input_format_t::json const bool strict true const bool ignore_comments false

generate SAX events

The SAX event lister must follow the interface of json_sax.

This function reads from a compatible input. Examples are:

- an std::istream object

- a FILE pointer

- a C-style array of characters

- a pointer to a null-terminated string of single byte characters

- an object obj for which begin(obj) and end(obj) produces a valid pair of iterators.

i

input to read from

sax

SAX event listener

format

the format to parse (JSON, CBOR, MessagePack, or UBJSON)

strict

whether the input has to be consumed completely

ignore_comments

whether comments should be ignored and treated like whitespace (true) or yield a parse error (true); (optional, false by default); only applies to the JSON file format.

return value of the last processed SAX event

parse_error.101

if a parse error occurs; example: `""unexpected end of input; expected string literal""`

parse_error.102

if to_unicode fails or surrogate error

parse_error.103

if to_unicode fails

Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the SAX consumer sax has a super-linear complexity.

A UTF-8 byte order mark is silently ignored.

{The example below demonstrates the `sax_parse()` function reading from string and processing the events with a user-defined SAX event consumer.,sax_parse}

version 3.2.0

nlohmann::detail::input_adapter
nlohmann::detail::json
JSON_HEDLEY_NON_NULL
nlohmann::detail::strict
class IteratorType
class SAX
bool static bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::sax_parse (IteratorType first, IteratorType last, SAX *sax, input_format_t format=input_format_t::json, const bool strict=true, const bool ignore_comments=false) sax_parse IteratorType first IteratorType last SAX * sax input_format_t format input_format_t::json const bool strict true const bool ignore_comments false nlohmann::detail::input_adapter nlohmann::detail::json JSON_HEDLEY_DEPRECATED_FOR JSON_HEDLEY_NON_NULL nlohmann::detail::strict
typename SAX
bool static bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::sax_parse (detail::span_input_adapter &&i, SAX *sax, input_format_t format=input_format_t::json, const bool strict=true, const bool ignore_comments=false) sax_parse detail::span_input_adapter && i SAX * sax input_format_t format input_format_t::json const bool strict true const bool ignore_comments false nlohmann::detail::json JSON_HEDLEY_DEPRECATED_FOR nlohmann::detail::strict
binary serialization/deserialization support
std::vector< uint8_t > static std::vector<uint8_t> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_cbor (const basic_json &j) to_cbor const basic_json & j

create a CBOR serialization of a given JSON value

Serializes a given JSON value j to a byte vector using the CBOR (Concise Binary Object Representation) serialization format. CBOR is a binary serialization format which aims to be more compact than JSON itself, yet more efficient to parse.

The library uses the following mapping from JSON values types to CBOR types according to the CBOR specification (RFC 7049):

JSON value type | value/range | CBOR type | first byte
null | `null` | Null | 0xF6
boolean | `true` | True | 0xF5
boolean | `false` | False | 0xF4
number_integer | -9223372036854775808..-2147483649 | Negative integer (8 bytes follow) | 0x3B
number_integer | -2147483648..-32769 | Negative integer (4 bytes follow) | 0x3A
number_integer | -32768..-129 | Negative integer (2 bytes follow) | 0x39
number_integer | -128..-25 | Negative integer (1 byte follow) | 0x38
number_integer | -24..-1 | Negative integer | 0x20..0x37
number_integer | 0..23 | Integer | 0x00..0x17
number_integer | 24..255 | Unsigned integer (1 byte follow) | 0x18
number_integer | 256..65535 | Unsigned integer (2 bytes follow) | 0x19
number_integer | 65536..4294967295 | Unsigned integer (4 bytes follow) | 0x1A
number_integer | 4294967296..18446744073709551615 | Unsigned integer (8 bytes follow) | 0x1B
number_unsigned | 0..23 | Integer | 0x00..0x17
number_unsigned | 24..255 | Unsigned integer (1 byte follow) | 0x18
number_unsigned | 256..65535 | Unsigned integer (2 bytes follow) | 0x19
number_unsigned | 65536..4294967295 | Unsigned integer (4 bytes follow) | 0x1A
number_unsigned | 4294967296..18446744073709551615 | Unsigned integer (8 bytes follow) | 0x1B
number_float | any value representable by a float | Single-Precision Float | 0xFA
number_float | any value NOT representable by a float | Double-Precision Float | 0xFB
string | length: 0..23 | UTF-8 string | 0x60..0x77
string | length: 23..255 | UTF-8 string (1 byte follow) | 0x78
string | length: 256..65535 | UTF-8 string (2 bytes follow) | 0x79
string | length: 65536..4294967295 | UTF-8 string (4 bytes follow) | 0x7A
string | length: 4294967296..18446744073709551615 | UTF-8 string (8 bytes follow) | 0x7B
array | size: 0..23 | array | 0x80..0x97
array | size: 23..255 | array (1 byte follow) | 0x98
array | size: 256..65535 | array (2 bytes follow) | 0x99
array | size: 65536..4294967295 | array (4 bytes follow) | 0x9A
array | size: 4294967296..18446744073709551615 | array (8 bytes follow) | 0x9B
object | size: 0..23 | map | 0xA0..0xB7
object | size: 23..255 | map (1 byte follow) | 0xB8
object | size: 256..65535 | map (2 bytes follow) | 0xB9
object | size: 65536..4294967295 | map (4 bytes follow) | 0xBA
object | size: 4294967296..18446744073709551615 | map (8 bytes follow) | 0xBB
binary | size: 0..23 | byte string | 0x40..0x57
binary | size: 23..255 | byte string (1 byte follow) | 0x58
binary | size: 256..65535 | byte string (2 bytes follow) | 0x59
binary | size: 65536..4294967295 | byte string (4 bytes follow) | 0x5A
binary | size: 4294967296..18446744073709551615 | byte string (8 bytes follow) | 0x5B

The mapping is complete in the sense that any JSON value type can be converted to a CBOR value.

If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the dump() function which serializes NaN or Infinity to `null`.

The following CBOR types are not used in the conversion:

- UTF-8 strings terminated by "break" (0x7F)

- arrays terminated by "break" (0x9F)

- maps terminated by "break" (0xBF)

- byte strings terminated by "break" (0x5F)

- date/time (0xC0..0xC1)

- bignum (0xC2..0xC3)

- decimal fraction (0xC4)

- bigfloat (0xC5)

- expected conversions (0xD5..0xD7)

- simple values (0xE0..0xF3, 0xF8)

- undefined (0xF7)

- half-precision floats (0xF9)

- break (0xFF)

j

JSON value to serialize

CBOR serialization as byte vector

Linear in the size of the JSON value j.

{The example shows the serialization of a JSON value to a byte vector in CBOR format.,to_cbor}

http://cbor.io

see from_cbor(InputType&&, const bool, const bool, const cbor_tag_handler_t) for the analogous deserialization

see to_msgpack(const basic_json&) for the related MessagePack format

see to_ubjson(const basic_json&, const bool, const bool) for the related UBJSON format

version 2.0.9; compact representation of floating-point numbers since version 3.8.0

void static void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_cbor (const basic_json &j, detail::output_adapter< uint8_t > o) to_cbor const basic_json & j detail::output_adapter< uint8_t > o
void static void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_cbor (const basic_json &j, detail::output_adapter< char > o) to_cbor const basic_json & j detail::output_adapter< char > o
std::vector< uint8_t > static std::vector<uint8_t> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_msgpack (const basic_json &j) to_msgpack const basic_json & j

create a MessagePack serialization of a given JSON value

Serializes a given JSON value j to a byte vector using the MessagePack serialization format. MessagePack is a binary serialization format which aims to be more compact than JSON itself, yet more efficient to parse.

The library uses the following mapping from JSON values types to MessagePack types according to the MessagePack specification:

JSON value type | value/range | MessagePack type | first byte
null | `null` | nil | 0xC0
boolean | `true` | true | 0xC3
boolean | `false` | false | 0xC2
number_integer | -9223372036854775808..-2147483649 | int64 | 0xD3
number_integer | -2147483648..-32769 | int32 | 0xD2
number_integer | -32768..-129 | int16 | 0xD1
number_integer | -128..-33 | int8 | 0xD0
number_integer | -32..-1 | negative fixint | 0xE0..0xFF
number_integer | 0..127 | positive fixint | 0x00..0x7F
number_integer | 128..255 | uint 8 | 0xCC
number_integer | 256..65535 | uint 16 | 0xCD
number_integer | 65536..4294967295 | uint 32 | 0xCE
number_integer | 4294967296..18446744073709551615 | uint 64 | 0xCF
number_unsigned | 0..127 | positive fixint | 0x00..0x7F
number_unsigned | 128..255 | uint 8 | 0xCC
number_unsigned | 256..65535 | uint 16 | 0xCD
number_unsigned | 65536..4294967295 | uint 32 | 0xCE
number_unsigned | 4294967296..18446744073709551615 | uint 64 | 0xCF
number_float | any value representable by a float | float 32 | 0xCA
number_float | any value NOT representable by a float | float 64 | 0xCB
string | length: 0..31 | fixstr | 0xA0..0xBF
string | length: 32..255 | str 8 | 0xD9
string | length: 256..65535 | str 16 | 0xDA
string | length: 65536..4294967295 | str 32 | 0xDB
array | size: 0..15 | fixarray | 0x90..0x9F
array | size: 16..65535 | array 16 | 0xDC
array | size: 65536..4294967295 | array 32 | 0xDD
object | size: 0..15 | fix map | 0x80..0x8F
object | size: 16..65535 | map 16 | 0xDE
object | size: 65536..4294967295 | map 32 | 0xDF
binary | size: 0..255 | bin 8 | 0xC4
binary | size: 256..65535 | bin 16 | 0xC5
binary | size: 65536..4294967295 | bin 32 | 0xC6

The mapping is complete in the sense that any JSON value type can be converted to a MessagePack value.

The following values can not be converted to a MessagePack value:

- strings with more than 4294967295 bytes

- byte strings with more than 4294967295 bytes

- arrays with more than 4294967295 elements

- objects with more than 4294967295 elements

Any MessagePack output created to_msgpack can be successfully parsed by from_msgpack.

If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the dump() function which serializes NaN or Infinity to `null`.

j

JSON value to serialize

MessagePack serialization as byte vector

Linear in the size of the JSON value j.

{The example shows the serialization of a JSON value to a byte vector in MessagePack format.,to_msgpack}

http://msgpack.org

see from_msgpack for the analogous deserialization

see to_cbor(const basic_json& for the related CBOR format

see to_ubjson(const basic_json&, const bool, const bool) for the related UBJSON format

version 2.0.9

void static void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_msgpack (const basic_json &j, detail::output_adapter< uint8_t > o) to_msgpack const basic_json & j detail::output_adapter< uint8_t > o
void static void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_msgpack (const basic_json &j, detail::output_adapter< char > o) to_msgpack const basic_json & j detail::output_adapter< char > o
std::vector< uint8_t > static std::vector<uint8_t> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_ubjson (const basic_json &j, const bool use_size=false, const bool use_type=false) to_ubjson const basic_json & j const bool use_size false const bool use_type false

create a UBJSON serialization of a given JSON value

Serializes a given JSON value j to a byte vector using the UBJSON (Universal Binary JSON) serialization format. UBJSON aims to be more compact than JSON itself, yet more efficient to parse.

The library uses the following mapping from JSON values types to UBJSON types according to the UBJSON specification:

JSON value type | value/range | UBJSON type | marker
null | `null` | null | `Z`
boolean | `true` | true | `T`
boolean | `false` | false | `F`
number_integer | -9223372036854775808..-2147483649 | int64 | `L`
number_integer | -2147483648..-32769 | int32 | `l`
number_integer | -32768..-129 | int16 | `I`
number_integer | -128..127 | int8 | `i`
number_integer | 128..255 | uint8 | `U`
number_integer | 256..32767 | int16 | `I`
number_integer | 32768..2147483647 | int32 | `l`
number_integer | 2147483648..9223372036854775807 | int64 | `L`
number_unsigned | 0..127 | int8 | `i`
number_unsigned | 128..255 | uint8 | `U`
number_unsigned | 256..32767 | int16 | `I`
number_unsigned | 32768..2147483647 | int32 | `l`
number_unsigned | 2147483648..9223372036854775807 | int64 | `L`
number_unsigned | 2147483649..18446744073709551615 | high-precision | `H`
number_float | any value | float64 | `D`
string | with shortest length indicator | string | `S`
array | see notes on optimized format | array | `[`
object | see notes on optimized format | map | `{`

The mapping is complete in the sense that any JSON value type can be converted to a UBJSON value.

The following values can not be converted to a UBJSON value:

- strings with more than 9223372036854775807 bytes (theoretical)

The following markers are not used in the conversion:

- `Z`: no-op values are not created.

- `C`: single-byte strings are serialized with `S` markers.

Any UBJSON output created to_ubjson can be successfully parsed by from_ubjson.

If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the dump() function which serializes NaN or Infinity to `null`.

The optimized formats for containers are supported: Parameter use_size adds size information to the beginning of a container and removes the closing marker. Parameter use_type further checks whether all elements of a container have the same type and adds the type marker to the beginning of the container. The use_type parameter must only be used together with use_size = true. Note that use_size = true alone may result in larger representations - the benefit of this parameter is that the receiving side is immediately informed on the number of elements of the container.

If the JSON data contains the binary type, the value stored is a list of integers, as suggested by the UBJSON documentation. In particular, this means that serialization and the deserialization of a JSON containing binary values into UBJSON and back will result in a different JSON object.

j

JSON value to serialize

use_size

whether to add size annotations to container types

use_type

whether to add type annotations to container types (must be combined with use_size = true)

UBJSON serialization as byte vector

Linear in the size of the JSON value j.

{The example shows the serialization of a JSON value to a byte vector in UBJSON format.,to_ubjson}

http://ubjson.org

see from_ubjson(InputType&&, const bool, const bool) for the analogous deserialization

see to_cbor(const basic_json& for the related CBOR format

see to_msgpack(const basic_json&) for the related MessagePack format

version 3.1.0

void static void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_ubjson (const basic_json &j, detail::output_adapter< uint8_t > o, const bool use_size=false, const bool use_type=false) to_ubjson const basic_json & j detail::output_adapter< uint8_t > o const bool use_size false const bool use_type false
void static void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_ubjson (const basic_json &j, detail::output_adapter< char > o, const bool use_size=false, const bool use_type=false) to_ubjson const basic_json & j detail::output_adapter< char > o const bool use_size false const bool use_type false
std::vector< uint8_t > static std::vector<uint8_t> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_bson (const basic_json &j) to_bson const basic_json & j

Serializes the given JSON object `j` to BSON and returns a vector containing the corresponding BSON-representation.

BSON (Binary JSON) is a binary format in which zero or more ordered key/value pairs are stored as a single entity (a so-called document).

The library uses the following mapping from JSON values types to BSON types:

JSON value type | value/range | BSON type | marker
null | `null` | null | 0x0A
boolean | `true`, `false` | boolean | 0x08
number_integer | -9223372036854775808..-2147483649 | int64 | 0x12
number_integer | -2147483648..2147483647 | int32 | 0x10
number_integer | 2147483648..9223372036854775807 | int64 | 0x12
number_unsigned | 0..2147483647 | int32 | 0x10
number_unsigned | 2147483648..9223372036854775807 | int64 | 0x12
number_unsigned | 9223372036854775808..18446744073709551615 |  |
number_float | any value | double | 0x01
string | any value | string | 0x02
array | any value | document | 0x04
object | any value | document | 0x03
binary | any value | binary | 0x05

The mapping is incomplete, since only JSON-objects (and things contained therein) can be serialized to BSON. Also, integers larger than 9223372036854775807 cannot be serialized to BSON, and the keys may not contain U+0000, since they are serialized a zero-terminated c-strings.

out_of_range.407

if `j.is_number_unsigned() && j.get<std::uint64_t>() > 9223372036854775807`

out_of_range.409

if a key in `j` contains a NULL (U+0000)

type_error.317

if `!j.is_object()`

The input `j` is required to be an object: `j.is_object() == true`.

Any BSON output created via to_bson can be successfully parsed by from_bson.

j

JSON value to serialize

BSON serialization as byte vector

Linear in the size of the JSON value j.

{The example shows the serialization of a JSON value to a byte vector in BSON format.,to_bson}

http://bsonspec.org/spec.html

see from_bson(detail::input_adapter&&, const bool strict) for the analogous deserialization

see to_ubjson(const basic_json&, const bool, const bool) for the related UBJSON format

see to_cbor(const basic_json&) for the related CBOR format

see to_msgpack(const basic_json&) for the related MessagePack format

void static void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_bson (const basic_json &j, detail::output_adapter< uint8_t > o) to_bson const basic_json & j detail::output_adapter< uint8_t > o

Serializes the given JSON object `j` to BSON and forwards the corresponding BSON-representation to the given output_adapter `o`.

j

The JSON object to convert to BSON.

o

The output adapter that receives the binary BSON representation.

The input `j` shall be an object: `j.is_object() == true`

see to_bson(const basic_json&)

void static void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::to_bson (const basic_json &j, detail::output_adapter< char > o) to_bson const basic_json & j detail::output_adapter< char > o

Serializes the given JSON object `j` to BSON and forwards the corresponding BSON-representation to the given output_adapter `o`.

j

The JSON object to convert to BSON.

o

The output adapter that receives the binary BSON representation.

The input `j` shall be an object: `j.is_object() == true`

see to_bson(const basic_json&)

JSON_HEDLEY_WARN_UNUSED_RESULT
typename InputType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_cbor (InputType &&i, const bool strict=true, const bool allow_exceptions=true, const cbor_tag_handler_t tag_handler=cbor_tag_handler_t::error) from_cbor InputType && i const bool strict true const bool allow_exceptions true const cbor_tag_handler_t tag_handler cbor_tag_handler_t::error

create a JSON value from an input in CBOR format

Deserializes a given input i to a JSON value using the CBOR (Concise Binary Object Representation) serialization format.

The library maps CBOR types to JSON value types as follows:

CBOR type | JSON value type | first byte
Integer | number_unsigned | 0x00..0x17
Unsigned integer | number_unsigned | 0x18
Unsigned integer | number_unsigned | 0x19
Unsigned integer | number_unsigned | 0x1A
Unsigned integer | number_unsigned | 0x1B
Negative integer | number_integer | 0x20..0x37
Negative integer | number_integer | 0x38
Negative integer | number_integer | 0x39
Negative integer | number_integer | 0x3A
Negative integer | number_integer | 0x3B
Byte string | binary | 0x40..0x57
Byte string | binary | 0x58
Byte string | binary | 0x59
Byte string | binary | 0x5A
Byte string | binary | 0x5B
UTF-8 string | string | 0x60..0x77
UTF-8 string | string | 0x78
UTF-8 string | string | 0x79
UTF-8 string | string | 0x7A
UTF-8 string | string | 0x7B
UTF-8 string | string | 0x7F
array | array | 0x80..0x97
array | array | 0x98
array | array | 0x99
array | array | 0x9A
array | array | 0x9B
array | array | 0x9F
map | object | 0xA0..0xB7
map | object | 0xB8
map | object | 0xB9
map | object | 0xBA
map | object | 0xBB
map | object | 0xBF
False | `false` | 0xF4
True | `true` | 0xF5
Null | `null` | 0xF6
Half-Precision Float | number_float | 0xF9
Single-Precision Float | number_float | 0xFA
Double-Precision Float | number_float | 0xFB

The mapping is incomplete in the sense that not all CBOR types can be converted to a JSON value. The following CBOR types are not supported and will yield parse errors (parse_error.112):

- date/time (0xC0..0xC1)

- bignum (0xC2..0xC3)

- decimal fraction (0xC4)

- bigfloat (0xC5)

- expected conversions (0xD5..0xD7)

- simple values (0xE0..0xF3, 0xF8)

- undefined (0xF7)

CBOR allows map keys of any type, whereas JSON only allows strings as keys in object values. Therefore, CBOR maps with keys other than UTF-8 strings are rejected (parse_error.113).

Any CBOR output created to_cbor can be successfully parsed by from_cbor.

i

an input in CBOR format convertible to an input adapter

strict

whether to expect the input to be consumed until EOF (true by default)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

tag_handler

how to treat CBOR tags (optional, error by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.110

if the given input ends prematurely or the end of file was not reached when strict was set to true

parse_error.112

if unsupported features from CBOR were used in the given input v or if the input is not valid CBOR

parse_error.113

if a string was expected as map key, but not found

Linear in the size of the input i.

{The example shows the deserialization of a byte vector in CBOR format to a JSON value.,from_cbor}

http://cbor.io

see to_cbor(const basic_json&) for the analogous serialization

see from_msgpack(InputType&&, const bool, const bool) for the related MessagePack format

see from_ubjson(InputType&&, const bool, const bool) for the related UBJSON format

version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0; added allow_exceptions parameter since 3.2.0; added tag_handler parameter since 3.9.0.

nlohmann::detail::cbor
nlohmann::detail::discarded
nlohmann::detail::input_adapter
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::detail::strict
typename IteratorType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_cbor (IteratorType first, IteratorType last, const bool strict=true, const bool allow_exceptions=true, const cbor_tag_handler_t tag_handler=cbor_tag_handler_t::error) from_cbor IteratorType first IteratorType last const bool strict true const bool allow_exceptions true const cbor_tag_handler_t tag_handler cbor_tag_handler_t::error

create a JSON value from an input in CBOR format

Deserializes a given input i to a JSON value using the CBOR (Concise Binary Object Representation) serialization format.

The library maps CBOR types to JSON value types as follows:

CBOR type | JSON value type | first byte
Integer | number_unsigned | 0x00..0x17
Unsigned integer | number_unsigned | 0x18
Unsigned integer | number_unsigned | 0x19
Unsigned integer | number_unsigned | 0x1A
Unsigned integer | number_unsigned | 0x1B
Negative integer | number_integer | 0x20..0x37
Negative integer | number_integer | 0x38
Negative integer | number_integer | 0x39
Negative integer | number_integer | 0x3A
Negative integer | number_integer | 0x3B
Byte string | binary | 0x40..0x57
Byte string | binary | 0x58
Byte string | binary | 0x59
Byte string | binary | 0x5A
Byte string | binary | 0x5B
UTF-8 string | string | 0x60..0x77
UTF-8 string | string | 0x78
UTF-8 string | string | 0x79
UTF-8 string | string | 0x7A
UTF-8 string | string | 0x7B
UTF-8 string | string | 0x7F
array | array | 0x80..0x97
array | array | 0x98
array | array | 0x99
array | array | 0x9A
array | array | 0x9B
array | array | 0x9F
map | object | 0xA0..0xB7
map | object | 0xB8
map | object | 0xB9
map | object | 0xBA
map | object | 0xBB
map | object | 0xBF
False | `false` | 0xF4
True | `true` | 0xF5
Null | `null` | 0xF6
Half-Precision Float | number_float | 0xF9
Single-Precision Float | number_float | 0xFA
Double-Precision Float | number_float | 0xFB

The mapping is incomplete in the sense that not all CBOR types can be converted to a JSON value. The following CBOR types are not supported and will yield parse errors (parse_error.112):

- date/time (0xC0..0xC1)

- bignum (0xC2..0xC3)

- decimal fraction (0xC4)

- bigfloat (0xC5)

- expected conversions (0xD5..0xD7)

- simple values (0xE0..0xF3, 0xF8)

- undefined (0xF7)

CBOR allows map keys of any type, whereas JSON only allows strings as keys in object values. Therefore, CBOR maps with keys other than UTF-8 strings are rejected (parse_error.113).

Any CBOR output created to_cbor can be successfully parsed by from_cbor.

i

an input in CBOR format convertible to an input adapter

strict

whether to expect the input to be consumed until EOF (true by default)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

tag_handler

how to treat CBOR tags (optional, error by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.110

if the given input ends prematurely or the end of file was not reached when strict was set to true

parse_error.112

if unsupported features from CBOR were used in the given input v or if the input is not valid CBOR

parse_error.113

if a string was expected as map key, but not found

Linear in the size of the input i.

{The example shows the deserialization of a byte vector in CBOR format to a JSON value.,from_cbor}

http://cbor.io

see to_cbor(const basic_json&) for the analogous serialization

see from_msgpack(InputType&&, const bool, const bool) for the related MessagePack format

see from_ubjson(InputType&&, const bool, const bool) for the related UBJSON format

version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0; added allow_exceptions parameter since 3.2.0; added tag_handler parameter since 3.9.0.

nlohmann::detail::cbor
nlohmann::detail::discarded
nlohmann::detail::input_adapter
JSON_HEDLEY_DEPRECATED_FOR
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::detail::strict
typename T
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_cbor (const T *ptr, std::size_t len, const bool strict=true, const bool allow_exceptions=true, const cbor_tag_handler_t tag_handler=cbor_tag_handler_t::error) from_cbor const T * ptr std::size_t len const bool strict true const bool allow_exceptions true const cbor_tag_handler_t tag_handler cbor_tag_handler_t::error JSON_HEDLEY_DEPRECATED_FOR JSON_HEDLEY_WARN_UNUSED_RESULT nlohmann::detail::strict
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_cbor (detail::span_input_adapter &&i, const bool strict=true, const bool allow_exceptions=true, const cbor_tag_handler_t tag_handler=cbor_tag_handler_t::error) from_cbor detail::span_input_adapter && i const bool strict true const bool allow_exceptions true const cbor_tag_handler_t tag_handler cbor_tag_handler_t::error nlohmann::detail::cbor nlohmann::detail::discarded JSON_HEDLEY_WARN_UNUSED_RESULT nlohmann::detail::strict
typename InputType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_msgpack (InputType &&i, const bool strict=true, const bool allow_exceptions=true) from_msgpack InputType && i const bool strict true const bool allow_exceptions true

create a JSON value from an input in MessagePack format

Deserializes a given input i to a JSON value using the MessagePack serialization format.

The library maps MessagePack types to JSON value types as follows:

MessagePack type | JSON value type | first byte
positive fixint | number_unsigned | 0x00..0x7F
fixmap | object | 0x80..0x8F
fixarray | array | 0x90..0x9F
fixstr | string | 0xA0..0xBF
nil | `null` | 0xC0
false | `false` | 0xC2
true | `true` | 0xC3
float 32 | number_float | 0xCA
float 64 | number_float | 0xCB
uint 8 | number_unsigned | 0xCC
uint 16 | number_unsigned | 0xCD
uint 32 | number_unsigned | 0xCE
uint 64 | number_unsigned | 0xCF
int 8 | number_integer | 0xD0
int 16 | number_integer | 0xD1
int 32 | number_integer | 0xD2
int 64 | number_integer | 0xD3
str 8 | string | 0xD9
str 16 | string | 0xDA
str 32 | string | 0xDB
array 16 | array | 0xDC
array 32 | array | 0xDD
map 16 | object | 0xDE
map 32 | object | 0xDF
bin 8 | binary | 0xC4
bin 16 | binary | 0xC5
bin 32 | binary | 0xC6
ext 8 | binary | 0xC7
ext 16 | binary | 0xC8
ext 32 | binary | 0xC9
fixext 1 | binary | 0xD4
fixext 2 | binary | 0xD5
fixext 4 | binary | 0xD6
fixext 8 | binary | 0xD7
fixext 16 | binary | 0xD8
negative fixint | number_integer | 0xE0-0xFF

Any MessagePack output created to_msgpack can be successfully parsed by from_msgpack.

i

an input in MessagePack format convertible to an input adapter

strict

whether to expect the input to be consumed until EOF (true by default)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.110

if the given input ends prematurely or the end of file was not reached when strict was set to true

parse_error.112

if unsupported features from MessagePack were used in the given input i or if the input is not valid MessagePack

parse_error.113

if a string was expected as map key, but not found

Linear in the size of the input i.

{The example shows the deserialization of a byte vector in MessagePack format to a JSON value.,from_msgpack}

http://msgpack.org

see to_msgpack(const basic_json&) for the analogous serialization

see from_cbor(InputType&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format

see from_ubjson(InputType&&, const bool, const bool) for the related UBJSON format

see from_bson(InputType&&, const bool, const bool) for the related BSON format

version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0; added allow_exceptions parameter since 3.2.0

nlohmann::detail::discarded
nlohmann::detail::input_adapter
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::detail::msgpack
nlohmann::detail::strict
typename IteratorType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_msgpack (IteratorType first, IteratorType last, const bool strict=true, const bool allow_exceptions=true) from_msgpack IteratorType first IteratorType last const bool strict true const bool allow_exceptions true

create a JSON value from an input in MessagePack format

Deserializes a given input i to a JSON value using the MessagePack serialization format.

The library maps MessagePack types to JSON value types as follows:

MessagePack type | JSON value type | first byte
positive fixint | number_unsigned | 0x00..0x7F
fixmap | object | 0x80..0x8F
fixarray | array | 0x90..0x9F
fixstr | string | 0xA0..0xBF
nil | `null` | 0xC0
false | `false` | 0xC2
true | `true` | 0xC3
float 32 | number_float | 0xCA
float 64 | number_float | 0xCB
uint 8 | number_unsigned | 0xCC
uint 16 | number_unsigned | 0xCD
uint 32 | number_unsigned | 0xCE
uint 64 | number_unsigned | 0xCF
int 8 | number_integer | 0xD0
int 16 | number_integer | 0xD1
int 32 | number_integer | 0xD2
int 64 | number_integer | 0xD3
str 8 | string | 0xD9
str 16 | string | 0xDA
str 32 | string | 0xDB
array 16 | array | 0xDC
array 32 | array | 0xDD
map 16 | object | 0xDE
map 32 | object | 0xDF
bin 8 | binary | 0xC4
bin 16 | binary | 0xC5
bin 32 | binary | 0xC6
ext 8 | binary | 0xC7
ext 16 | binary | 0xC8
ext 32 | binary | 0xC9
fixext 1 | binary | 0xD4
fixext 2 | binary | 0xD5
fixext 4 | binary | 0xD6
fixext 8 | binary | 0xD7
fixext 16 | binary | 0xD8
negative fixint | number_integer | 0xE0-0xFF

Any MessagePack output created to_msgpack can be successfully parsed by from_msgpack.

i

an input in MessagePack format convertible to an input adapter

strict

whether to expect the input to be consumed until EOF (true by default)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.110

if the given input ends prematurely or the end of file was not reached when strict was set to true

parse_error.112

if unsupported features from MessagePack were used in the given input i or if the input is not valid MessagePack

parse_error.113

if a string was expected as map key, but not found

Linear in the size of the input i.

{The example shows the deserialization of a byte vector in MessagePack format to a JSON value.,from_msgpack}

http://msgpack.org

see to_msgpack(const basic_json&) for the analogous serialization

see from_cbor(InputType&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format

see from_ubjson(InputType&&, const bool, const bool) for the related UBJSON format

see from_bson(InputType&&, const bool, const bool) for the related BSON format

version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0; added allow_exceptions parameter since 3.2.0

nlohmann::detail::discarded
nlohmann::detail::input_adapter
JSON_HEDLEY_DEPRECATED_FOR
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::detail::msgpack
nlohmann::detail::strict
typename T
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_msgpack (const T *ptr, std::size_t len, const bool strict=true, const bool allow_exceptions=true) from_msgpack const T * ptr std::size_t len const bool strict true const bool allow_exceptions true JSON_HEDLEY_DEPRECATED_FOR JSON_HEDLEY_WARN_UNUSED_RESULT nlohmann::detail::strict
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_msgpack (detail::span_input_adapter &&i, const bool strict=true, const bool allow_exceptions=true) from_msgpack detail::span_input_adapter && i const bool strict true const bool allow_exceptions true nlohmann::detail::discarded JSON_HEDLEY_WARN_UNUSED_RESULT nlohmann::detail::msgpack nlohmann::detail::strict
typename InputType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_ubjson (InputType &&i, const bool strict=true, const bool allow_exceptions=true) from_ubjson InputType && i const bool strict true const bool allow_exceptions true

create a JSON value from an input in UBJSON format

Deserializes a given input i to a JSON value using the UBJSON (Universal Binary JSON) serialization format.

The library maps UBJSON types to JSON value types as follows:

UBJSON type | JSON value type | marker
no-op | no value, next value is read | `N`
null | `null` | `Z`
false | `false` | `F`
true | `true` | `T`
float32 | number_float | `d`
float64 | number_float | `D`
uint8 | number_unsigned | `U`
int8 | number_integer | `i`
int16 | number_integer | `I`
int32 | number_integer | `l`
int64 | number_integer | `L`
high-precision number | number_integer, number_unsigned, or number_float - depends on number string | 'H'
string | string | `S`
char | string | `C`
array | array (optimized values are supported) | `[`
object | object (optimized values are supported) | `{`

The mapping is complete in the sense that any UBJSON value can be converted to a JSON value.

i

an input in UBJSON format convertible to an input adapter

strict

whether to expect the input to be consumed until EOF (true by default)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.110

if the given input ends prematurely or the end of file was not reached when strict was set to true

parse_error.112

if a parse error occurs

parse_error.113

if a string could not be parsed successfully

Linear in the size of the input i.

{The example shows the deserialization of a byte vector in UBJSON format to a JSON value.,from_ubjson}

http://ubjson.org

see to_ubjson(const basic_json&, const bool, const bool) for the analogous serialization

see from_cbor(InputType&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format

see from_msgpack(InputType&&, const bool, const bool) for the related MessagePack format

see from_bson(InputType&&, const bool, const bool) for the related BSON format

version 3.1.0; added allow_exceptions parameter since 3.2.0

nlohmann::detail::discarded
nlohmann::detail::input_adapter
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::detail::strict
nlohmann::detail::ubjson
typename IteratorType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_ubjson (IteratorType first, IteratorType last, const bool strict=true, const bool allow_exceptions=true) from_ubjson IteratorType first IteratorType last const bool strict true const bool allow_exceptions true

create a JSON value from an input in UBJSON format

Deserializes a given input i to a JSON value using the UBJSON (Universal Binary JSON) serialization format.

The library maps UBJSON types to JSON value types as follows:

UBJSON type | JSON value type | marker
no-op | no value, next value is read | `N`
null | `null` | `Z`
false | `false` | `F`
true | `true` | `T`
float32 | number_float | `d`
float64 | number_float | `D`
uint8 | number_unsigned | `U`
int8 | number_integer | `i`
int16 | number_integer | `I`
int32 | number_integer | `l`
int64 | number_integer | `L`
high-precision number | number_integer, number_unsigned, or number_float - depends on number string | 'H'
string | string | `S`
char | string | `C`
array | array (optimized values are supported) | `[`
object | object (optimized values are supported) | `{`

The mapping is complete in the sense that any UBJSON value can be converted to a JSON value.

i

an input in UBJSON format convertible to an input adapter

strict

whether to expect the input to be consumed until EOF (true by default)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.110

if the given input ends prematurely or the end of file was not reached when strict was set to true

parse_error.112

if a parse error occurs

parse_error.113

if a string could not be parsed successfully

Linear in the size of the input i.

{The example shows the deserialization of a byte vector in UBJSON format to a JSON value.,from_ubjson}

http://ubjson.org

see to_ubjson(const basic_json&, const bool, const bool) for the analogous serialization

see from_cbor(InputType&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format

see from_msgpack(InputType&&, const bool, const bool) for the related MessagePack format

see from_bson(InputType&&, const bool, const bool) for the related BSON format

version 3.1.0; added allow_exceptions parameter since 3.2.0

nlohmann::detail::discarded
nlohmann::detail::input_adapter
JSON_HEDLEY_DEPRECATED_FOR
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::detail::strict
nlohmann::detail::ubjson
typename T
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_ubjson (const T *ptr, std::size_t len, const bool strict=true, const bool allow_exceptions=true) from_ubjson const T * ptr std::size_t len const bool strict true const bool allow_exceptions true JSON_HEDLEY_DEPRECATED_FOR JSON_HEDLEY_WARN_UNUSED_RESULT nlohmann::detail::strict
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_ubjson (detail::span_input_adapter &&i, const bool strict=true, const bool allow_exceptions=true) from_ubjson detail::span_input_adapter && i const bool strict true const bool allow_exceptions true nlohmann::detail::discarded JSON_HEDLEY_WARN_UNUSED_RESULT nlohmann::detail::strict nlohmann::detail::ubjson
typename InputType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_bson (InputType &&i, const bool strict=true, const bool allow_exceptions=true) from_bson InputType && i const bool strict true const bool allow_exceptions true

Create a JSON value from an input in BSON format.

Deserializes a given input i to a JSON value using the BSON (Binary JSON) serialization format.

The library maps BSON record types to JSON value types as follows:

BSON type | BSON marker byte | JSON value type
double | 0x01 | number_float
string | 0x02 | string
document | 0x03 | object
array | 0x04 | array
binary | 0x05 | binary
undefined | 0x06 | still unsupported
ObjectId | 0x07 | still unsupported
boolean | 0x08 | boolean
UTC Date-Time | 0x09 | still unsupported
null | 0x0A | null
Regular Expr. | 0x0B | still unsupported
DB Pointer | 0x0C | still unsupported
JavaScript Code | 0x0D | still unsupported
Symbol | 0x0E | still unsupported
JavaScript Code | 0x0F | still unsupported
int32 | 0x10 | number_integer
Timestamp | 0x11 | still unsupported
128-bit decimal float | 0x13 | still unsupported
Max Key | 0x7F | still unsupported
Min Key | 0xFF | still unsupported

The mapping is incomplete. The unsupported mappings are indicated in the table above.

i

an input in BSON format convertible to an input adapter

strict

whether to expect the input to be consumed until EOF (true by default)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.114

if an unsupported BSON record type is encountered

Linear in the size of the input i.

{The example shows the deserialization of a byte vector in BSON format to a JSON value.,from_bson}

http://bsonspec.org/spec.html

see to_bson(const basic_json&) for the analogous serialization

see from_cbor(InputType&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format

see from_msgpack(InputType&&, const bool, const bool) for the related MessagePack format

see from_ubjson(InputType&&, const bool, const bool) for the related UBJSON format

nlohmann::detail::bson
nlohmann::detail::discarded
nlohmann::detail::input_adapter
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::detail::strict
typename IteratorType
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_bson (IteratorType first, IteratorType last, const bool strict=true, const bool allow_exceptions=true) from_bson IteratorType first IteratorType last const bool strict true const bool allow_exceptions true

Create a JSON value from an input in BSON format.

Deserializes a given input i to a JSON value using the BSON (Binary JSON) serialization format.

The library maps BSON record types to JSON value types as follows:

BSON type | BSON marker byte | JSON value type
double | 0x01 | number_float
string | 0x02 | string
document | 0x03 | object
array | 0x04 | array
binary | 0x05 | binary
undefined | 0x06 | still unsupported
ObjectId | 0x07 | still unsupported
boolean | 0x08 | boolean
UTC Date-Time | 0x09 | still unsupported
null | 0x0A | null
Regular Expr. | 0x0B | still unsupported
DB Pointer | 0x0C | still unsupported
JavaScript Code | 0x0D | still unsupported
Symbol | 0x0E | still unsupported
JavaScript Code | 0x0F | still unsupported
int32 | 0x10 | number_integer
Timestamp | 0x11 | still unsupported
128-bit decimal float | 0x13 | still unsupported
Max Key | 0x7F | still unsupported
Min Key | 0xFF | still unsupported

The mapping is incomplete. The unsupported mappings are indicated in the table above.

i

an input in BSON format convertible to an input adapter

strict

whether to expect the input to be consumed until EOF (true by default)

allow_exceptions

whether to throw exceptions in case of a parse error (optional, true by default)

deserialized JSON value; in case of a parse error and allow_exceptions set to `false`, the return value will be value_t::discarded.

parse_error.114

if an unsupported BSON record type is encountered

Linear in the size of the input i.

{The example shows the deserialization of a byte vector in BSON format to a JSON value.,from_bson}

http://bsonspec.org/spec.html

see to_bson(const basic_json&) for the analogous serialization

see from_cbor(InputType&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format

see from_msgpack(InputType&&, const bool, const bool) for the related MessagePack format

see from_ubjson(InputType&&, const bool, const bool) for the related UBJSON format

nlohmann::detail::bson
nlohmann::detail::discarded
nlohmann::detail::input_adapter
JSON_HEDLEY_DEPRECATED_FOR
JSON_HEDLEY_WARN_UNUSED_RESULT
nlohmann::detail::strict
typename T
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_bson (const T *ptr, std::size_t len, const bool strict=true, const bool allow_exceptions=true) from_bson const T * ptr std::size_t len const bool strict true const bool allow_exceptions true JSON_HEDLEY_DEPRECATED_FOR JSON_HEDLEY_WARN_UNUSED_RESULT nlohmann::detail::strict
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::from_bson (detail::span_input_adapter &&i, const bool strict=true, const bool allow_exceptions=true) from_bson detail::span_input_adapter && i const bool strict true const bool allow_exceptions true nlohmann::detail::bson nlohmann::detail::discarded nlohmann::detail::strict
JSON Pointer functions
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] (const json_pointer &ptr) operator[] const json_pointer & ptr

access specified element via JSON Pointer

Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. Similar to operator[](const typename object_t::key_type&), `null` values are created in arrays and objects if necessary.

In particular:

- If the JSON pointer points to an object key that does not exist, it is created an filled with a `null` value before a reference to it is returned.

- If the JSON pointer points to an array index that does not exist, it is created an filled with a `null` value before a reference to it is returned. All indices between the current maximum and the given index are also filled with `null`.

- The special value `-` is treated as a synonym for the index past the end.

ptr

a JSON pointer

reference to the element pointed to by ptr

Constant.

parse_error.106

if an array index begins with '0'

parse_error.109

if an array index was not a number

out_of_range.404

if the JSON pointer can not be resolved

{The behavior is shown in the example.,operatorjson_pointer}

version 2.0.0

nlohmann::json_pointer< BasicJsonType >::get_unchecked
const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] (const json_pointer &ptr) const operator[] const json_pointer & ptr

access specified element via JSON Pointer

Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. The function does not change the JSON value; no `null` values are created. In particular, the special value `-` yields an exception.

ptr

JSON pointer to the desired element

const reference to the element pointed to by ptr

Constant.

parse_error.106

if an array index begins with '0'

parse_error.109

if an array index was not a number

out_of_range.402

if the array index '-' is used

out_of_range.404

if the JSON pointer can not be resolved

{The behavior is shown in the example.,operatorjson_pointer_const}

version 2.0.0

nlohmann::json_pointer< BasicJsonType >::get_unchecked
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::at (const json_pointer &ptr) at const json_pointer & ptr

access specified element via JSON Pointer

Returns a reference to the element at with specified JSON pointer ptr, with bounds checking.

ptr

JSON pointer to the desired element

reference to the element pointed to by ptr

parse_error.106

if an array index in the passed JSON pointer ptr begins with '0'. See example below.

parse_error.109

if an array index in the passed JSON pointer ptr is not a number. See example below.

out_of_range.401

if an array index in the passed JSON pointer ptr is out of range. See example below.

out_of_range.402

if the array index '-' is used in the passed JSON pointer ptr. As `at` provides checked access (and no elements are implicitly inserted), the index '-' is always invalid. See example below.

out_of_range.403

if the JSON pointer describes a key of an object which cannot be found. See example below.

out_of_range.404

if the JSON pointer ptr can not be resolved. See example below.

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Constant.

version 2.0.0

{The behavior is shown in the example.,at_json_pointer}
nlohmann::json_pointer< BasicJsonType >::get_checked
const_reference const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::at (const json_pointer &ptr) const at const json_pointer & ptr

access specified element via JSON Pointer

Returns a const reference to the element at with specified JSON pointer ptr, with bounds checking.

ptr

JSON pointer to the desired element

reference to the element pointed to by ptr

parse_error.106

if an array index in the passed JSON pointer ptr begins with '0'. See example below.

parse_error.109

if an array index in the passed JSON pointer ptr is not a number. See example below.

out_of_range.401

if an array index in the passed JSON pointer ptr is out of range. See example below.

out_of_range.402

if the array index '-' is used in the passed JSON pointer ptr. As `at` provides checked access (and no elements are implicitly inserted), the index '-' is always invalid. See example below.

out_of_range.403

if the JSON pointer describes a key of an object which cannot be found. See example below.

out_of_range.404

if the JSON pointer ptr can not be resolved. See example below.

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Constant.

version 2.0.0

{The behavior is shown in the example.,at_json_pointer_const}
nlohmann::json_pointer< BasicJsonType >::get_checked
basic_json basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::flatten () const flatten

return flattened JSON value

The function creates a JSON object whose keys are JSON pointers (see RFC 6901) and whose values are all primitive. The original JSON value can be restored using the unflatten() function.

an object that maps JSON pointers to primitive values

Empty objects and arrays are flattened to `null` and will not be reconstructed correctly by the unflatten() function.

Linear in the size the JSON value.

{The following code shows how a JSON object is flattened to an object whose keys consist of JSON pointers.,flatten}

see unflatten() for the reverse function

version 2.0.0

nlohmann::json_pointer< BasicJsonType >::flatten
nlohmann::detail::object
basic_json basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::unflatten () const unflatten

unflatten a previously flattened JSON value

The function restores the arbitrary nesting of a JSON value that has been flattened before using the flatten() function. The JSON value must meet certain constraints:

1. The value must be an object.

2. The keys must be JSON pointers (see RFC 6901)

3. The mapped values must be primitive JSON types.

the original JSON from a flattened version

Empty objects and arrays are flattened by flatten() to `null` values and can not unflattened to their original type. Apart from this example, for a JSON value `j`, the following is always true: `j == j.flatten().unflatten()`.

Linear in the size the JSON value.

type_error.314

if value is not an object

type_error.315

if object values are not primitive

{The following code shows how a flattened JSON object is unflattened into the original nested JSON object.,unflatten}

see flatten() for the reverse function

version 2.0.0

nlohmann::json_pointer< BasicJsonType >::unflatten
JSON Patch functions
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::diff (const basic_json &source, const basic_json &target, const std::string &path="") diff const basic_json & source const basic_json & target const std::string & path ""

creates a diff as a JSON patch

Creates a JSON Patch so that value source can be changed into the value target by calling patch function.

For two JSON values source and target, the following code yields always `true`:

    source.patch(diff(source,target))==target;

Currently, only `remove`, `add`, and `replace` operations are generated.

source

JSON value to compare from

target

JSON value to compare against

path

helper value to create JSON pointers

a JSON patch to convert the source to target

Linear in the lengths of source and target.

{The following code shows how a JSON patch is created as a diff for two JSON values.,diff}

see patch apply a JSON patch

see merge_patch apply a JSON Merge Patch

RFC 6902 (JSON Patch)

version 2.0.0

nlohmann::detail::array
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::begin
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::cbegin
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::cend
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::end
nlohmann::detail::escape
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::find
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert
nlohmann::detail::object
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::push_back
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::size
nlohmann::to_string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::type
basic_json basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::patch (const basic_json &json_patch) const patch const basic_json & json_patch

applies a JSON patch

JSON Patch defines a JSON document structure for expressing a sequence of operations to apply to a JSON) document. With this function, a JSON Patch is applied to the current JSON value by executing all operations from the patch.

json_patch

JSON patch document

patched document

The application of a patch is atomic: Either all operations succeed and the patched document is returned or an exception is thrown. In any case, the original value is not changed: the patch is applied to a copy of the value.

parse_error.104

if the JSON patch does not consist of an array of objects

parse_error.105

if the JSON patch is malformed (e.g., mandatory attributes are missing); example: `"operation add must have member path"`

out_of_range.401

if an array index is out of range.

out_of_range.403

if a JSON pointer inside the patch could not be resolved successfully in the current JSON value; example: `"key baz not found"`

out_of_range.405

if JSON pointer has no parent ("add", "remove", "move")

other_error.501

if "test" operation was unsuccessful

Linear in the size of the JSON value and the length of the JSON patch. As usually only a fraction of the JSON value is affected by the patch, the complexity can usually be neglected.

{The following code shows how a JSON patch is applied to a value.,patch}

see diff create a JSON patch by comparing two JSON values

RFC 6902 (JSON Patch)

RFC 6901 (JSON Pointer)

version 2.0.0

nlohmann::detail::array
nlohmann::json_pointer< BasicJsonType >::array_index
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::at
nlohmann::json_pointer< BasicJsonType >::back
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::begin
nlohmann::detail::parse_error::create
nlohmann::detail::out_of_range::create
nlohmann::detail::other_error::create
nlohmann::json_pointer< BasicJsonType >::empty
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::end
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::erase
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::find
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::insert
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_array
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_object
JSON_ASSERT
JSON_HEDLEY_LIKELY
JSON_HEDLEY_UNLIKELY
JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_INTERNAL_CATCH
JSON_THROW
JSON_TRY
nlohmann::detail::null
nlohmann::detail::object
nlohmann::json_pointer< BasicJsonType >::pop_back
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::push_back
nlohmann::detail::replace
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::size
nlohmann::detail::string
nlohmann::to_string
JSON Merge Patch functions
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::merge_patch (const basic_json &apply_patch) merge_patch const basic_json & apply_patch

applies a JSON Merge Patch

The merge patch format is primarily intended for use with the HTTP PATCH method as a means of describing a set of modifications to a target resource's content. This function applies a merge patch to the current JSON value.

The function implements the following algorithm from Section 2 of RFC 7396 (JSON Merge Patch):

    defineMergePatch(Target,Patch):
    ifPatchisanObject:
    ifTargetisnotanObject:
    Target={}//IgnorethecontentsandsetittoanemptyObject
    foreachName/ValuepairinPatch:
    ifValueisnull:
    ifNameexistsinTarget:
    removetheName/ValuepairfromTarget
    else:
    Target[Name]=MergePatch(Target[Name],Value)
    returnTarget
    else:
    returnPatch

Thereby, `Target` is the current object; that is, the patch is applied to the current value.

apply_patch

the patch to apply

Linear in the lengths of patch.

{The following code shows how a JSON Merge Patch is applied to a JSON document.,merge_patch}

see patch apply a JSON patch

RFC 7396 (JSON Merge Patch)

version 3.0.0

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::begin
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::end
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_object
NLOHMANN_BASIC_JSON_TPL_DECLARATION
nlohmann::detail::object
NLOHMANN_BASIC_JSON_TPL using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json_t = NLOHMANN_BASIC_JSON_TPL basic_json_t

workaround type for MSVC

::nlohmann::detail::primitive_iterator_t using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::primitive_iterator_t = ::nlohmann::detail::primitive_iterator_t primitive_iterator_t
::nlohmann::detail::internal_iterator< BasicJsonType > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::internal_iterator = ::nlohmann::detail::internal_iterator<BasicJsonType> internal_iterator
::nlohmann::detail::iter_impl< BasicJsonType > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::iter_impl = ::nlohmann::detail::iter_impl<BasicJsonType> iter_impl
::nlohmann::detail::iteration_proxy< Iterator > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::iteration_proxy = ::nlohmann::detail::iteration_proxy<Iterator> iteration_proxy
::nlohmann::detail::json_reverse_iterator< Base > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_reverse_iterator = ::nlohmann::detail::json_reverse_iterator<Base> json_reverse_iterator
::nlohmann::detail::output_adapter_t< CharType > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::output_adapter_t = ::nlohmann::detail::output_adapter_t<CharType> output_adapter_t
::nlohmann::detail::binary_reader< basic_json, InputType > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::binary_reader = ::nlohmann::detail::binary_reader<basic_json, InputType> binary_reader
::nlohmann::detail::binary_writer< basic_json, CharType > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::binary_writer = ::nlohmann::detail::binary_writer<basic_json, CharType> binary_writer
detail::value_t using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::value_t = detail::value_t value_t
::nlohmann::json_pointer< basic_json > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_pointer = ::nlohmann::json_pointer<basic_json> json_pointer

JSON Pointer, see nlohmann::json_pointer.

JSONSerializer< T, SFINAE > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_serializer = JSONSerializer<T, SFINAE> json_serializer
detail::error_handler_t using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::error_handler_t = detail::error_handler_t error_handler_t

how to treat decoding errors

detail::cbor_tag_handler_t using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::cbor_tag_handler_t = detail::cbor_tag_handler_t cbor_tag_handler_t

how to treat CBOR tags

std::initializer_list< detail::json_ref< basic_json > > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::initializer_list_t = std::initializer_list<detail::json_ref<basic_json> > initializer_list_t

helper type for initializer lists of basic_json values

detail::input_format_t using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::input_format_t = detail::input_format_t input_format_t
json_sax< basic_json > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_sax_t = json_sax<basic_json> json_sax_t

SAX interface type, see nlohmann::json_sax.

detail::parse_event_t using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parse_event_t = detail::parse_event_t parse_event_t

parser event types

The parser callback distinguishes the following events:

- `object_start`: the parser read `{` and started to process a JSON object

- `key`: the parser read a key of a value in an object

- `object_end`: the parser read `}` and finished processing a JSON object

- `array_start`: the parser read `[` and started to process a JSON array

- `array_end`: the parser read `]` and finished processing a JSON array

- `value`: the parser finished reading a JSON value

Example when certain parse events are triggered

see parser_callback_t for more information and examples

detail::parser_callback_t< basic_json > using nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parser_callback_t = detail::parser_callback_t<basic_json> parser_callback_t

per-element parser callback type

With a parser callback function, the result of parsing a JSON text can be influenced. When passed to parse, it is called on certain events (passed as parse_event_t via parameter event) with a set recursion depth depth and context JSON value parsed. The return value of the callback function is a boolean indicating whether the element that emitted the callback shall be kept or not.

We distinguish six scenarios (determined by the event type) in which the callback function can be called. The following table describes the values of the parameters depth, event, and parsed.

parameter event | description | parameter depth | parameter parsed
parse_event_t::object_start | the parser read `{` and started to process a JSON object | depth of the parent of the JSON object | a JSON value with type discarded
parse_event_t::key | the parser read a key of a value in an object | depth of the currently parsed JSON object | a JSON string containing the key
parse_event_t::object_end | the parser read `}` and finished processing a JSON object | depth of the parent of the JSON object | the parsed JSON object
parse_event_t::array_start | the parser read `[` and started to process a JSON array | depth of the parent of the JSON array | a JSON value with type discarded
parse_event_t::array_end | the parser read `]` and finished processing a JSON array | depth of the parent of the JSON array | the parsed JSON array
parse_event_t::value | the parser finished reading a JSON value | depth of the value | the parsed JSON value

Example when certain parse events are triggered Discarding a value (i.e., returning `false`) has different effects depending on the context in which function was called:

- Discarded values in structured types are skipped. That is, the parser will behave as if the discarded value was never read.

- In case a value outside a structured type is skipped, it is replaced with `null`. This case happens if the top-level element is skipped.

depth

the depth of the recursion during parsing

event

an event of type parse_event_t indicating the context in the callback function has been called

parsed

the current intermediate parse result; note that writing to this value has no effect for parse_event_t::key events

Whether the JSON value which called the function during parsing should be kept (`true`) or not (`false`). In the latter case, it is either skipped completely or replaced by an empty discarded object.

see parse for examples

version 1.0.0

detail::value_t
friend struct friend struct detail::external_constructor detail::external_constructor
typename BasicJsonType
typename InputType
friend class friend class ::nlohmann::detail::parser ::nlohmann::detail::parser
typename BasicJsonType
friend class friend class ::nlohmann::detail::iter_impl ::nlohmann::detail::iter_impl
typename BasicJsonType
typename CharType
friend class friend class ::nlohmann::detail::binary_writer ::nlohmann::detail::binary_writer
typename BasicJsonType
typename InputType
typename SAX
friend class friend class ::nlohmann::detail::binary_reader ::nlohmann::detail::binary_reader
typename BasicJsonType
friend class friend class ::nlohmann::detail::json_sax_dom_parser ::nlohmann::detail::json_sax_dom_parser
typename BasicJsonType
friend class friend class ::nlohmann::detail::json_sax_dom_callback_parser ::nlohmann::detail::json_sax_dom_callback_parser
friend class friend class ::nlohmann::detail::exception ::nlohmann::detail::exception
JSON_PRIVATE_UNLESS_TESTED JSON_PRIVATE_UNLESS_TESTED nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::__pad0__ __pad0__ using lexer = ::nlohmann::detail::lexer_base<basic_json>
JSON_PRIVATE_UNLESS_TESTED JSON_PRIVATE_UNLESS_TESTED nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::__pad1__ __pad1__ using serializer = ::nlohmann::detail::serializer<basic_json>
JSON_PRIVATE_UNLESS_TESTED JSON_PRIVATE_UNLESS_TESTED nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::__pad2__ __pad2__ union json_value { object_t* object
array_t * array_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::array array

array (stored with pointer to save storage)

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[]
string_t * string_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::string string

string (stored with pointer to save storage)

binary_t * binary_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::binary binary

binary (stored with pointer to save storage)

boolean_t boolean_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::boolean boolean

boolean

number_integer_t number_integer_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::number_integer number_integer

number (integer)

number_unsigned_t number_unsigned_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::number_unsigned number_unsigned

number (unsigned integer)

number_float_t number_float_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::number_float number_float

number (floating-point)

JSON_PRIVATE_UNLESS_TESTED JSON_PRIVATE_UNLESS_TESTED nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::__pad3__ __pad3__ value_t m_type = value_t::null
json_value json_value nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::m_value m_value = {}

the value of the current element

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::destroy
typename InputAdapterType
::nlohmann::detail::parser< basic_json, InputAdapterType > static ::nlohmann::detail::parser<basic_json, InputAdapterType> nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::parser (InputAdapterType adapter, detail::parser_callback_t< basic_json >cb=nullptr, const bool allow_exceptions=true, const bool ignore_comments=false) parser InputAdapterType adapter detail::parser_callback_t< basic_json > cb nullptr const bool allow_exceptions true const bool ignore_comments false
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
()=default
json_value

default constructor (for null values)

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(boolean_t v) noexcept
json_value
boolean_t v

constructor for booleans

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(number_integer_t v) noexcept
json_value
number_integer_t v

constructor for numbers (integer)

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(number_unsigned_t v) noexcept
json_value
number_unsigned_t v

constructor for numbers (unsigned)

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(number_float_t v) noexcept
json_value
number_float_t v

constructor for numbers (floating-point)

nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(value_t t)
json_value
value_t t

constructor for empty values of a given type

nlohmann::detail::array
nlohmann::detail::binary
nlohmann::detail::boolean
nlohmann::detail::other_error::create
JSON_HEDLEY_UNLIKELY
JSON_THROW
nlohmann::detail::null
nlohmann::detail::number_float
nlohmann::detail::number_integer
nlohmann::detail::number_unsigned
nlohmann::detail::object
nlohmann::detail::string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(const string_t &value)
json_value
const string_t & value

constructor for strings

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(string_t &&value)
json_value
string_t && value

constructor for rvalue strings

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(const object_t &value)
json_value
const object_t & value

constructor for objects

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(object_t &&value)
json_value
object_t && value

constructor for rvalue objects

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(const array_t &value)
json_value
const array_t & value

constructor for arrays

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(array_t &&value)
json_value
array_t && value

constructor for rvalue arrays

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(const typename binary_t::container_type &value)
json_value
const typename binary_t::container_type & value

constructor for binary arrays

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(typename binary_t::container_type &&value)
json_value
typename binary_t::container_type && value

constructor for rvalue binary arrays

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(const binary_t &value)
json_value
const binary_t & value

constructor for binary arrays (internal type)

nlohmann::detail::value
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::json_value
(binary_t &&value)
json_value
binary_t && value

constructor for rvalue binary arrays (internal type)

nlohmann::detail::value
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::destroy (value_t t) noexcept destroy value_t t nlohmann::detail::array nlohmann::detail::binary nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_array nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_object nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::m_value nlohmann::detail::object nlohmann::detail::string
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::assert_invariant (bool check_parents=true) const noexcept assert_invariant bool check_parents true

checks the class invariants

This function asserts the class invariants. It needs to be called at the end of every constructor to make sure that created objects respect the invariant. Furthermore, it has to be called each time the type of a JSON value is changed, because the invariant expresses a relationship between m_type and m_value.

Furthermore, the parent relation is checked for arrays and objects: If check_parents true and the value is an array or object, then the container's elements must have the current value as parent.

check_parents

whether the parent relation should be checked. The value is true by default and should only be set to false during destruction of objects when the invariant does not need to hold.

nlohmann::detail::array
nlohmann::detail::binary
JSON_ASSERT
JSON_CATCH
JSON_TRY
nlohmann::detail::object
nlohmann::detail::string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::basic_json
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator=
void void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::set_parents () set_parents nlohmann::detail::array nlohmann::detail::object
iterator iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::set_parents (iterator it, typename iterator::difference_type count) set_parents iterator it typename iterator::difference_type count
reference reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::set_parent (reference j) set_parent reference j
boolean_t boolean_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl (boolean_t *) const get_impl boolean_t *

get a boolean (explicit)

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
object_t * object_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (object_t *) noexcept get_impl_ptr object_t *

get a pointer to the value (object)

constexpr const object_t * constexpr const object_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (const object_t *) const noexcept get_impl_ptr const object_t *

get a pointer to the value (object)

array_t * array_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (array_t *) noexcept get_impl_ptr array_t *

get a pointer to the value (array)

constexpr const array_t * constexpr const array_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (const array_t *) const noexcept get_impl_ptr const array_t *

get a pointer to the value (array)

string_t * string_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (string_t *) noexcept get_impl_ptr string_t *

get a pointer to the value (string)

constexpr const string_t * constexpr const string_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (const string_t *) const noexcept get_impl_ptr const string_t *

get a pointer to the value (string)

boolean_t * boolean_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (boolean_t *) noexcept get_impl_ptr boolean_t *

get a pointer to the value (boolean)

constexpr const boolean_t * constexpr const boolean_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (const boolean_t *) const noexcept get_impl_ptr const boolean_t *

get a pointer to the value (boolean)

number_integer_t * number_integer_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (number_integer_t *) noexcept get_impl_ptr number_integer_t *

get a pointer to the value (integer number)

constexpr const number_integer_t * constexpr const number_integer_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (const number_integer_t *) const noexcept get_impl_ptr const number_integer_t *

get a pointer to the value (integer number)

number_unsigned_t * number_unsigned_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (number_unsigned_t *) noexcept get_impl_ptr number_unsigned_t *

get a pointer to the value (unsigned number)

constexpr const number_unsigned_t * constexpr const number_unsigned_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (const number_unsigned_t *) const noexcept get_impl_ptr const number_unsigned_t *

get a pointer to the value (unsigned number)

number_float_t * number_float_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (number_float_t *) noexcept get_impl_ptr number_float_t *

get a pointer to the value (floating-point number)

constexpr const number_float_t * constexpr const number_float_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (const number_float_t *) const noexcept get_impl_ptr const number_float_t *

get a pointer to the value (floating-point number)

binary_t * binary_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (binary_t *) noexcept get_impl_ptr binary_t *

get a pointer to the value (binary)

constexpr const binary_t * constexpr const binary_t* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_impl_ptr (const binary_t *) const noexcept get_impl_ptr const binary_t *

get a pointer to the value (binary)

allocator_type static allocator_type nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_allocator () get_allocator

returns the allocator associated with the container

JSON_HEDLEY_WARN_UNUSED_RESULT
JSON_HEDLEY_WARN_UNUSED_RESULT basic_json static JSON_HEDLEY_WARN_UNUSED_RESULT basic_json nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::meta () meta

returns version information on the library

This function returns a JSON object with information about the library, including the version number and information on the platform and compiler.

JSON object holding version information

key | description
`compiler` | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version).
`copyright` | The copyright line for the library as string.
`name` | The name of the library as string.
`platform` | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`.
`url` | The URL of the project as string.
`version` | The version of the library. It is an object with the following keys: `major`, `minor`, and `patch` as defined by Semantic Versioning, and `string` (the version string).

{The following code shows an example output of the `meta()` function.,meta}
Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

Constant.

2.1.0

NLOHMANN_JSON_VERSION_MAJOR
NLOHMANN_JSON_VERSION_MINOR
NLOHMANN_JSON_VERSION_PATCH
nlohmann::to_string
typename T
typename... Args Args
JSON_HEDLEY_RETURNS_NON_NULL T * static JSON_HEDLEY_RETURNS_NON_NULL T* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::create (Args &&... args) create Args &&... args

helper for exception-safe object creation

JSON_ASSERT
JSON_PRIVATE_UNLESS_TESTED
typename ReferenceType
typename ThisType
ReferenceType static ReferenceType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::get_ref_impl (ThisType &obj) get_ref_impl ThisType & obj

helper function to implement get_ref()

This function helps to implement get_ref() without code duplication for const and non-const overloads

ThisType

will be deduced as `basic_json` or `const basic_json`

type_error.303

if ReferenceType does not match underlying value type of the current JSON

nlohmann::detail::type_error::create
JSON_HEDLEY_LIKELY
JSON_THROW
nlohmann::detail::string
JSON_HEDLEY_RETURNS_NON_NULL const char * JSON_HEDLEY_RETURNS_NON_NULL const char* nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::type_name () const noexcept type_name

return the type as string

Returns the type name as string to be used in error messages - usually to indicate that a function was called on a wrong JSON type.

a string representation of a the m_type member:

Value type | return value
null | `"null"`
boolean | `"boolean"`
string | `"string"`
number | `"number"` (for all number types)
object | `"object"`
array | `"array"`
binary | `"binary"`
discarded | `"discarded"`

No-throw guarantee: this function never throws exceptions.
Constant.

{The following code exemplifies `type_name()` for all JSON types.,type_name}

see type() return the type of the JSON value

see operator value_t() return the type of the JSON value (implicit)

version 1.0.0, public since 2.1.0, `const char*` and `noexcept` since 3.0.0

nlohmann::detail::array
nlohmann::detail::binary
nlohmann::detail::boolean
nlohmann::detail::discarded
JSON_PRIVATE_UNLESS_TESTED
nlohmann::detail::null
nlohmann::detail::object
nlohmann::detail::string
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::update

a class to store JSON values

ObjectType

type for JSON objects (`std::map` by default; will be used in object_t)

ArrayType

type for JSON arrays (`std::vector` by default; will be used in array_t)

StringType

type for JSON strings and object keys (`std::string` by default; will be used in string_t)

BooleanType

type for JSON booleans (`bool` by default; will be used in boolean_t)

NumberIntegerType

type for JSON integer numbers (`int64_t` by default; will be used in number_integer_t)

NumberUnsignedType

type for JSON unsigned integer numbers (``uint64_t`` by default; will be used in number_unsigned_t)

NumberFloatType

type for JSON floating-point numbers (`double` by default; will be used in number_float_t)

BinaryType

type for packed binary data for compatibility with binary serialization formats (`std::vector<std::uint8_t>` by default; will be used in binary_t)

AllocatorType

type of the allocator to use (`std::allocator` by default)

JSONSerializer

the serializer to resolve internal calls to `to_json()` and `from_json()` (adl_serializer by default)

The class satisfies the following concept requirements:

- Basic

  - DefaultConstructible: JSON values can be default constructed. The result will be a JSON null value.

  - MoveConstructible: A JSON value can be constructed from an rvalue argument.

  - CopyConstructible: A JSON value can be copy-constructed from an lvalue expression.

  - MoveAssignable: A JSON value van be assigned from an rvalue argument.

  - CopyAssignable: A JSON value can be copy-assigned from an lvalue expression.

  - Destructible: JSON values can be destructed.

- Layout

  - StandardLayoutType: JSON values have standard layout: All non-static data members are private and standard layout types, the class has no virtual functions or (virtual) base classes.

- Library-wide

  - EqualityComparable: JSON values can be compared with `==`, see operator==(const_reference,const_reference).

  - LessThanComparable: JSON values can be compared with `<`, see operator<(const_reference,const_reference).

  - Swappable: Any JSON lvalue or rvalue of can be swapped with any lvalue or rvalue of other compatible types, using unqualified function call swap().

  - NullablePointer: JSON values can be compared against `std::nullptr_t` objects which are used to model the `null` value.

- Container

  - Container: JSON values can be used like STL containers and provide iterator access.

  - ReversibleContainer; JSON values can be used like STL containers and provide reverse iterator access.

The member variables m_value and m_type have the following relationship:

- If `m_type == value_t::object`, then `m_value.object != nullptr`.

- If `m_type == value_t::array`, then `m_value.array != nullptr`.

- If `m_type == value_t::string`, then `m_value.string != nullptr`. The invariants are checked by member function assert_invariant().

RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format

version 1.0.0

BooleanType
JSON_PRIVATE_UNLESS_TESTED
NumberUnsignedType
BinaryType
array_t *
NumberFloatType
string_t *
uint8_t
bool
nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >
+m_value
-number_integer
-number_float
-number_unsigned
-binary
-string
-boolean
-array
-__pad2__
-__pad1__
-__pad0__
+__pad3__
NumberIntegerType
nlohmann::byte_container_with_subtype< BinaryType >
-m_subtype
-m_has_subtype
json_value
- nlohmann::basic_json
  ::nlohmann::detail::binary_reader
- nlohmann::basic_json
  ::nlohmann::detail::binary_writer
- nlohmann::basic_json
  ::nlohmann::detail::exception
- nlohmann::basic_json
  ::nlohmann::detail::iter_impl
- nlohmann::basic_json
  ::nlohmann::detail::json_sax_dom_callback_parser
- nlohmann::basic_json
  ::nlohmann::detail::json_sax_dom_parser
- nlohmann::basic_json
  ::nlohmann::detail::parser
- nlohmann::basic_json
  __pad0__
- nlohmann::basic_json
  __pad1__
- nlohmann::basic_json
  __pad2__
- nlohmann::basic_json
  __pad3__
- nlohmann::basic_json
  accept
- nlohmann::basic_json
  accept
- nlohmann::basic_json
  accept
- nlohmann::basic_json
  allocator_type
- nlohmann::basic_json
  array
- nlohmann::basic_json
  array
- nlohmann::basic_json
  array_t
- nlohmann::basic_json
  assert_invariant
- nlohmann::basic_json
  at
- nlohmann::basic_json
  at
- nlohmann::basic_json
  at
- nlohmann::basic_json
  at
- nlohmann::basic_json
  at
- nlohmann::basic_json
  at
- nlohmann::basic_json
  back
- nlohmann::basic_json
  back
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json
- nlohmann::basic_json
  basic_json_t
- nlohmann::basic_json
  begin
- nlohmann::basic_json
  begin
- nlohmann::basic_json
  binary
- nlohmann::basic_json
  binary
- nlohmann::basic_json
  binary
- nlohmann::basic_json
  binary
- nlohmann::basic_json
  binary
- nlohmann::basic_json
  binary_reader
- nlohmann::basic_json
  binary_t
- nlohmann::basic_json
  binary_writer
- nlohmann::basic_json
  boolean
- nlohmann::basic_json
  boolean_t
- nlohmann::basic_json
  cbegin
- nlohmann::basic_json
  cbor_tag_handler_t
- nlohmann::basic_json
  cend
- nlohmann::basic_json
  clear
- nlohmann::basic_json
  const_iterator
- nlohmann::basic_json
  const_pointer
- nlohmann::basic_json
  const_reference
- nlohmann::basic_json
  const_reverse_iterator
- nlohmann::basic_json
  contains
- nlohmann::basic_json
  contains
- nlohmann::basic_json
  count
- nlohmann::basic_json
  crbegin
- nlohmann::basic_json
  create
- nlohmann::basic_json
  crend
- nlohmann::basic_json
  destroy
- nlohmann::basic_json
  detail::external_constructor
- nlohmann::basic_json
  diff
- nlohmann::basic_json
  difference_type
- nlohmann::basic_json
  dump
- nlohmann::basic_json
  emplace
- nlohmann::basic_json
  emplace_back
- nlohmann::basic_json
  empty
- nlohmann::basic_json
  end
- nlohmann::basic_json
  end
- nlohmann::basic_json
  erase
- nlohmann::basic_json
  erase
- nlohmann::basic_json
  erase
- nlohmann::basic_json
  erase
- nlohmann::basic_json
  error_handler_t
- nlohmann::basic_json
  exception
- nlohmann::basic_json
  find
- nlohmann::basic_json
  find
- nlohmann::basic_json
  flatten
- nlohmann::basic_json
  from_bson
- nlohmann::basic_json
  from_bson
- nlohmann::basic_json
  from_bson
- nlohmann::basic_json
  from_bson
- nlohmann::basic_json
  from_cbor
- nlohmann::basic_json
  from_cbor
- nlohmann::basic_json
  from_cbor
- nlohmann::basic_json
  from_cbor
- nlohmann::basic_json
  from_msgpack
- nlohmann::basic_json
  from_msgpack
- nlohmann::basic_json
  from_msgpack
- nlohmann::basic_json
  from_msgpack
- nlohmann::basic_json
  from_ubjson
- nlohmann::basic_json
  from_ubjson
- nlohmann::basic_json
  from_ubjson
- nlohmann::basic_json
  from_ubjson
- nlohmann::basic_json
  front
- nlohmann::basic_json
  front
- nlohmann::basic_json
  get
- nlohmann::basic_json
  get
- nlohmann::basic_json
  get_allocator
- nlohmann::basic_json
  get_binary
- nlohmann::basic_json
  get_binary
- nlohmann::basic_json
  get_impl
- nlohmann::basic_json
  get_impl
- nlohmann::basic_json
  get_impl
- nlohmann::basic_json
  get_impl
- nlohmann::basic_json
  get_impl
- nlohmann::basic_json
  get_impl
- nlohmann::basic_json
  get_impl
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_impl_ptr
- nlohmann::basic_json
  get_ptr
- nlohmann::basic_json
  get_ptr
- nlohmann::basic_json
  get_ref
- nlohmann::basic_json
  get_ref
- nlohmann::basic_json
  get_ref_impl
- nlohmann::basic_json
  get_to
- nlohmann::basic_json
  get_to
- nlohmann::basic_json
  get_to
- nlohmann::basic_json
  initializer_list_t
- nlohmann::basic_json
  input_format_t
- nlohmann::basic_json
  insert
- nlohmann::basic_json
  insert
- nlohmann::basic_json
  insert
- nlohmann::basic_json
  insert
- nlohmann::basic_json
  insert
- nlohmann::basic_json
  insert
- nlohmann::basic_json
  insert_iterator
- nlohmann::basic_json
  internal_iterator
- nlohmann::basic_json
  invalid_iterator
- nlohmann::basic_json
  is_array
- nlohmann::basic_json
  is_binary
- nlohmann::basic_json
  is_boolean
- nlohmann::basic_json
  is_discarded
- nlohmann::basic_json
  is_null
- nlohmann::basic_json
  is_number
- nlohmann::basic_json
  is_number_float
- nlohmann::basic_json
  is_number_integer
- nlohmann::basic_json
  is_number_unsigned
- nlohmann::basic_json
  is_object
- nlohmann::basic_json
  is_primitive
- nlohmann::basic_json
  is_string
- nlohmann::basic_json
  is_structured
- nlohmann::basic_json
  items
- nlohmann::basic_json
  items
- nlohmann::basic_json
  iter_impl
- nlohmann::basic_json
  iteration_proxy
- nlohmann::basic_json
  iterator
- nlohmann::basic_json
  iterator_wrapper
- nlohmann::basic_json
  iterator_wrapper
- nlohmann::basic_json
  json_pointer
- nlohmann::basic_json
  json_reverse_iterator
- nlohmann::basic_json
  json_sax_t
- nlohmann::basic_json
  json_serializer
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  json_value
- nlohmann::basic_json
  m_value
- nlohmann::basic_json
  max_size
- nlohmann::basic_json
  merge_patch
- nlohmann::basic_json
  meta
- nlohmann::basic_json
  number_float
- nlohmann::basic_json
  number_float_t
- nlohmann::basic_json
  number_integer
- nlohmann::basic_json
  number_integer_t
- nlohmann::basic_json
  number_unsigned
- nlohmann::basic_json
  number_unsigned_t
- nlohmann::basic_json
  object
- nlohmann::basic_json
  object_comparator_t
- nlohmann::basic_json
  object_t
- nlohmann::basic_json
  operator value_t
- nlohmann::basic_json
  operator ValueType
- nlohmann::basic_json
  operator!=
- nlohmann::basic_json
  operator!=
- nlohmann::basic_json
  operator!=
- nlohmann::basic_json
  operator+=
- nlohmann::basic_json
  operator+=
- nlohmann::basic_json
  operator+=
- nlohmann::basic_json
  operator+=
- nlohmann::basic_json
  operator<
- nlohmann::basic_json
  operator<
- nlohmann::basic_json
  operator<
- nlohmann::basic_json
  operator<<
- nlohmann::basic_json
  operator<<
- nlohmann::basic_json
  operator<=
- nlohmann::basic_json
  operator<=
- nlohmann::basic_json
  operator<=
- nlohmann::basic_json
  operator=
- nlohmann::basic_json
  operator==
- nlohmann::basic_json
  operator==
- nlohmann::basic_json
  operator==
- nlohmann::basic_json
  operator>
- nlohmann::basic_json
  operator>
- nlohmann::basic_json
  operator>
- nlohmann::basic_json
  operator>=
- nlohmann::basic_json
  operator>=
- nlohmann::basic_json
  operator>=
- nlohmann::basic_json
  operator>>
- nlohmann::basic_json
  operator>>
- nlohmann::basic_json
  operator[]
- nlohmann::basic_json
  operator[]
- nlohmann::basic_json
  operator[]
- nlohmann::basic_json
  operator[]
- nlohmann::basic_json
  operator[]
- nlohmann::basic_json
  operator[]
- nlohmann::basic_json
  operator[]
- nlohmann::basic_json
  operator[]
- nlohmann::basic_json
  other_error
- nlohmann::basic_json
  out_of_range
- nlohmann::basic_json
  output_adapter_t
- nlohmann::basic_json
  parse
- nlohmann::basic_json
  parse
- nlohmann::basic_json
  parse
- nlohmann::basic_json
  parse_error
- nlohmann::basic_json
  parse_event_t
- nlohmann::basic_json
  parser
- nlohmann::basic_json
  parser_callback_t
- nlohmann::basic_json
  patch
- nlohmann::basic_json
  pointer
- nlohmann::basic_json
  primitive_iterator_t
- nlohmann::basic_json
  push_back
- nlohmann::basic_json
  push_back
- nlohmann::basic_json
  push_back
- nlohmann::basic_json
  push_back
- nlohmann::basic_json
  rbegin
- nlohmann::basic_json
  rbegin
- nlohmann::basic_json
  reference
- nlohmann::basic_json
  rend
- nlohmann::basic_json
  rend
- nlohmann::basic_json
  reverse_iterator
- nlohmann::basic_json
  sax_parse
- nlohmann::basic_json
  sax_parse
- nlohmann::basic_json
  sax_parse
- nlohmann::basic_json
  set_parent
- nlohmann::basic_json
  set_parents
- nlohmann::basic_json
  set_parents
- nlohmann::basic_json
  size
- nlohmann::basic_json
  size_type
- nlohmann::basic_json
  string
- nlohmann::basic_json
  string_t
- nlohmann::basic_json
  swap
- nlohmann::basic_json
  swap
- nlohmann::basic_json
  swap
- nlohmann::basic_json
  swap
- nlohmann::basic_json
  swap
- nlohmann::basic_json
  swap
- nlohmann::basic_json
  swap
- nlohmann::basic_json
  to_bson
- nlohmann::basic_json
  to_bson
- nlohmann::basic_json
  to_bson
- nlohmann::basic_json
  to_cbor
- nlohmann::basic_json
  to_cbor
- nlohmann::basic_json
  to_cbor
- nlohmann::basic_json
  to_msgpack
- nlohmann::basic_json
  to_msgpack
- nlohmann::basic_json
  to_msgpack
- nlohmann::basic_json
  to_ubjson
- nlohmann::basic_json
  to_ubjson
- nlohmann::basic_json
  to_ubjson
- nlohmann::basic_json
  type
- nlohmann::basic_json
  type_error
- nlohmann::basic_json
  type_name
- nlohmann::basic_json
  unflatten
- nlohmann::basic_json
  update
- nlohmann::basic_json
  update
- nlohmann::basic_json
  value
- nlohmann::basic_json
  value
- nlohmann::basic_json
  value
- nlohmann::basic_json
  value
- nlohmann::basic_json
  value_t
- nlohmann::basic_json
  value_type
- nlohmann::basic_json
  ~basic_json