What does a “CALLBACK” declaration in C do?

Question

I was looking through some code from the SDL library and came across a function declared like this:

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wPar         


        

Answer 1

The "CALLBACK" is a calling convention. There are other kinds of calling conventions. CALLBACK is the same as __stdcall.

http://www.codeguru.com/cpp/cpp/cpp_mfc/callbacks/article.php/c10557

Some more information at Raymond Chen's blog:

http://blogs.msdn.com/oldnewthing/archive/2004/01/08/48616.aspx