1 #ifdef EXTRA_FUNCTION foo(int i)2 int foo(int i) { 3 return i*3; 4 } 5 #endif 6 main(int argc,char const * argv[])7 int main (int argc, char const *argv[]) { 8 #ifdef EXTRA_FUNCTION 9 return foo(argc); 10 #else 11 return 0; 12 #endif 13 } 14