GCC dump preprocessor defines

Question

Is there a way for gcc/g++ to dump its preprocessor defines from the command line? I mean things like __GNUC__, __STDC__, and so on.

Answer 1

While working in a big project which has complex build system and where it is hard to get (or modify) the gcc/g++ command directly there is another way to see the result of macro expansion. Simply redefine the macro, and you will get output similiar to following:

file.h: note: this is the location of the previous definition
#define MACRO current_value