c - 为什么是这个输出？

Question

这是代码:

# include <stdio.h> 
# define scanf  "%s Geeks For Geeks " 
main() 
{ 
    printf(scanf, scanf); 
    getchar(); 
    return 0; 
}

输出是:%s Geeks For Geeks Geeks For Geeks

这个输出是如何生成的？

Answer 1

你的 printf 将变成

printf(scanf, scanf);

         |
         |
        \ /

printf("%s Geeks For Geeks ", "%s Geeks For Geeks" ); 

         |
         |       //%s is replaced with "%s Geeks For Geeks" string
        \ /

printf("%s Geeks For Geeks Geeks For Geeks ");

在控制台上

%s Geeks For Geeks Geeks For Geeks

Aside: Please don't do this kind of coding. It sucks.