why use EOF to check if stdin buffer is cleared

问题:

Say I have the following...

int main () {     
   char name [5] = "";
   char c;
   printf("Enter a name: ");
   fgets(name,5,stdin);
   while ((c = getchar()) != '\n');
   printf("Exiting...);
   getchar();
   return 0;
}

The while loop will clean the stdin buffer but I have seen the loop done like this as well...

while ((c = getchar()) != '\n' && c != EOF);

I am wondering if there is any difference between the 2??? Does testing for EOF make any difference?

回答1:

I am wondering if there is any difference between the 2??? Does testing for EOF make any difference?

Yes, testing c != EOF makes a tremendous difference. getchar() returns EOF in the event that it detects an error or end-of-file on the standard input. Both of those are entirely possible. Once getchar() returns EOF, it is likely to return EOF again on every subsequent call, so the version that does not test for EOF is at risk of going into an infinite loop.