loesung-3.c

#include <stdio.h>

int fun_1 (char *s1, char *s2)
{
  int result = 1;
  for (int i = 0; s1[i] && s2[i]; i++)
    if (s1[i] != s2[i])
      result = 0;
  return result;
}

int fun_2 (char *s1, char *s2)
{
  int result = 1;
  for (int i = 0; s1[i] && s2[i] && result; i++)
    if (s1[i] != s2[i])
      result = 0;
  return result;
}

int fun_3 (char *s1, char *s2)
{
  for (int i = 0; s1[i] && s2[i]; i++)
    if (s1[i] != s2[i])
      return 0;
  return 1;
}

int fun_4 (char *s1, char *s2)
{
  int result = 1;
  for (int i = 0; s1[i] && s2[i]; i++)
    if (s1[i] != s2[i])
      {
        result = 0;
        break;
      }
  return result;
}

int main (void)
{
  char *s1 = "Apfel";
  char *s2 = "Apfelkuchen";
  if (fun_1 (s1, s2) && fun_2 (s1, s2) && fun_3 (s1, s2) && fun_4 (s1, s2))
    printf ("OK\n");
  else
    printf ("failed\n");
  s1 = "Apfelkuchen";
  s2 = "Apfel";
  if (fun_1 (s1, s2) && fun_2 (s1, s2) && fun_3 (s1, s2) && fun_4 (s1, s2))
    printf ("OK\n");
  else
    printf ("failed\n");
  s2 = "Birnenmarmelade";
  if (fun_1 (s1, s2) || fun_2 (s1, s2) || fun_3 (s1, s2) || fun_4 (s1, s2))
    printf ("failed\n");
  else
    printf ("OK\n");
  s1 = s2;
  s2 = "Apfelkuchen";
  if (fun_1 (s1, s2) || fun_2 (s1, s2) || fun_3 (s1, s2) || fun_4 (s1, s2))
    printf ("failed\n");
  else
    printf ("OK\n");
  return 0;
}