Quote Originally Posted by ArdentAngel View Post
error C2653: 'aa_physics' : is not a class or namespace name
error C3861: 'distance': identifier not found
Header files are used for class definitions and function declarations. cpp files are used for (member) function definitions. You include header files in cpp files or in other header files.
So your main.h file should probably be a main.cpp file and you should include "aa_physics.h" in it rather than the other way round.
Quote Originally Posted by ArdentAngel View Post
So, do you know any really good C++ programming books?
Since you already have some programming experience, Accelerated C++ by Koenig and Moo will be a good choice. It doesn't cover everything in depth, but it teaches you C++ the way professionals use it from the start.