EOF

case.c

#include <stdio.h>
#include <ctype.h>

int main() {  
  int c;
  while ((c = getchar()) != EOF) {
    putchar(toupper(c));
  }
  return 0;
}

case2.c

#include <stdio.h>
#include <ctype.h>

int main() {  
  int c;
  while (1) {
    c = getchar();
    putchar(toupper(c));
  }
  return 0;
}