Gave circular_buffer a constructor that takes the size.

dlib/sliding_buffer/circular_buffer.h

@@ -26,7 +26,11 @@ namespace dlib
 
         circular_buffer()
         {
-            offset = 0;
+        }
+
+        explicit circular_buffer(unsigned long s)
+        {
+            resize(s);
         }
 
         void clear (
@@ -149,7 +153,7 @@ namespace dlib
     private:
         std::vector<T> data;
 
-        unsigned long offset;
+        unsigned long offset = 0;
     };
 
 // ----------------------------------------------------------------------------------------

dlib/sliding_buffer/circular_buffer_abstract.h

@@ -49,6 +49,15 @@ namespace dlib
                 - this object is properly initialized
         !*/
 
+        explicit circular_buffer(
+            unsigned long s
+        );
+        /*!
+            ensures
+                - #size() == s
+                - this object is properly initialized
+        !*/
+
         void clear (
         );
         /*!