comma separated expression in while loop in C

Question

I never saw such a while statement before.

while(printf(\"> \"), fgets(str, 100, stdin), !feof(stdin)) {
..
..
}

I read

Answer 1

while(printf("> "), fgets(str, 100, stdin), !feof(stdin)) {
..
..
}

Commas inside a while behaves more like this:

int feof_wrapper(FILE * stream)
{
   printf("> ");
   fgets(str, 100, stream);
   return feof(stream);
}

while(!feof_wrapper(stdin)) {
..
..
}