How does the below program output `C89` when compiled in C89 mode and `C99` when compiled in C99 mode?

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 3  2006

I\'ve found this C program from the web:

#include 

int main(){

    printf(\"C%d\\n\",(int)(90-(-4.5//**/
    -4.5)));

    return 0;
}

3条回答

2021-01-30 05:22

C99 allows //-style comments, C89 does not. So, to translate:

C99:

 printf("C%d\n",(int)(90-(-4.5     /*Some  comment stuff*/
                         -4.5)));
// Outputs: 99

C89:

printf("C%d\n",(int)(90-(-4.5/      
                         -4.5)));
/* so  we get 90-1 or 89 */

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