The most useful user-made C-macros (in GCC, also C99)? [closed]

Answer 1

#if defined NDEBUG
    #define TRACE( format, ... )
#else
    #define TRACE( format, ... )   printf( "%s::%s(%d)" format, __FILE__, __FUNCTION__,  __LINE__, __VA_ARGS__ )
#endif

Note that the lack of a comma between "%s::%s(%d)" and format is deliberate. It prints a formatted string with source location prepended. I work in real-time embedded systems so often I also include a timestamp in the output as well.