An evil way to test debug macro: ./debug.c BEGIN! ./debug.c:main:19: test! ./debug.c:main:20: test! END ! BEGIN! END !

debug.c

#ifdef SHELL
gcc  $0 && ./a.out
gcc  -DNDEBUG $0 && ./a.out  
exit 0
#endif

#include <stdio.h>

#ifndef NDEBUG
#define DEBUG(fmt, arg...)	\
	fprintf(stderr, __FILE__ ":%s:%d: " fmt,__FUNCTION__,__LINE__,##arg)
#else
#define DEBUG(fmt, args...) 
#endif

int main( int argc, char * argv [] ) {
   printf("BEGIN!\n");
   DEBUG("test!\n");
   DEBUG("%s", "test!\n");
   printf("END !\n");
}