c++ - Compiler acts as if a preprocessor directive isn't defined -

i have header file , cpp file (error.h, error.cpp). cpp file performs check on preprocessor directive fails.

error.h:

/* optional macros: ae_exit_at_error ae_console_write_at_error */ #pragma once  extern void aeerror(const char *str, int code=1);  extern void aeassert(bool b, const char *failstr = "assertion failed"); 

error.cpp:

#include "error.h" #include <stdexcept> #ifdef ae_console_write_at_error #include <iostream> #endif  void aeerror(const char *str, int code) {     #ifdef ae_console_write_at_error     std::cout << str << std::endl;     #endif      throw std::runtime_error(str);      #ifdef ae_exit_at_error     std::exit(code);     #endif }  void aeassert(bool b, const char *failstr) {     if(!b)         aeerror(failstr); } 

main.cpp:

//define both macros: #define ae_console_write_at_error #define ae_exit_at_error #include "error.h"  //rest of code //... 

both std::cout << str << std::endl; , std::exit(code); don't compiled (i checked "manually", although marked gray ide, vs2010).

what might cause of this?

main.cpp , error.cpp different translation units. define macro main.cpp, not error.cpp.

you should either put #define directives in header file included both .cpp files, or define these macros in project settings/makefile.