// test special #if 0 treatment int main() { #if 0 // equivalent to a comment int i = 10; printf("this should never be executed\n"); # ifdef FOO printf("foo\n"); # ifndef BAR printf("no bar\n"); # else # endif # else printf("no foo\n"); # endif // FOO return 1; #else printf("Hello world!\n"); return 0; #endif printf("never reach here!\n"); }