Thread: c puzzle

For those who like to keep your mind sharp or for those who want to test their skills in programming here is an interesting C programming bug:

Code:

#include <stdio.h>
#include <unistd.h>

int main(int argc, char **argv)
{
  while(1) {
    fprintf(stdout, "out \t");
    fprintf(stderr, "err \t");
    sleep(1);
  }
    
  return 0;
}

This program will not print on the screen "out".. can you say why?