Forward Declaration of a Base Class

Question

I\'m trying to create proper header files which don\'t include too many other files to keep them clean and to speed up compile time.

I encountered two problems while

Answer 1

For your base classes, you need to have the full type definition, not just a declaration. Derived type headers will need to #include the header for their base classes.

For classes in the std namespace, you must include the proper header - in this case - and then do one of 3 things:

1. Fully qualify the type: std::string aStringToTest

2. Put a using declaration for just that type: using std::string;

3. Put in a using declaration for the std namespace: using namespace std;