What is the point of defining a calling convention?

Question

For example:

int WINAPI WinMain ( HINSTANCE instance, HINSTANCE prev_instance, PSTR cmd_line, int cmd_show )

WINAPI is a a define that looks li

Answer 1

Because WINAPI is a macro (well a #define anyway) it can be "pre-processed" to mean something else or even nothing at all.

That means you can write more portable code, as you can put in WINAPI when it is required by Win32 to mean __stdcall but, or if it is required in another environment to mean something else or nothing.