Separate files cannot see definitions

[sigutis]

Hello. I have a problem with c ( not c++ )
Lets say I have a header system.h

#define PC 

And other file load.h

#include "system.h"

#ifdef PC
blablabla
#endif 

But blablabla never gets executed. Am I missing something here?

[helios]

PC should be defined in load.h after including system.h unless there's another included header #undefing it.