#include <stdio.h>
#define STR "Believe yourself\n"
int main(){
#ifdef STR
printf(STR);
#else
printf("**Dont't give up**\n");
#endif
printf("\n");
#ifndef ABC
printf("Don't give up\n");
#else
printf(STR);
#endif
return 0;
}
#ifdef和#ifndef的应用
#include <stdio.h>
#define STR "Believe yourself\n"
int main(){
#ifdef STR
printf(STR);
#else
printf("**Dont't give up**\n");
#endif
printf("\n");
#ifndef ABC
printf("Don't give up\n");
#else
printf(STR);
#endif
return 0;
}
