1b8e80941Smrg#if defined(foo) 2b8e80941Smrgfailure_1 3b8e80941Smrg#else 4b8e80941Smrgsuccess_1 5b8e80941Smrg#endif 6b8e80941Smrg#define foo 7b8e80941Smrg#if defined ( foo ) 8b8e80941Smrgsuccess_2 9b8e80941Smrg#else 10b8e80941Smrgfailure_2 11b8e80941Smrg#endif 12b8e80941Smrg#undef foo 13b8e80941Smrg#if defined (foo) 14b8e80941Smrgfailure_3 15b8e80941Smrg#else 16b8e80941Smrgsuccess_3 17b8e80941Smrg#endif 18