/* Programmed by Kurt Nørmark, April 2003 */

#include <stdio.h>
#include <string.h>

/* Assume as a precondition that both s1 and s2 are '0' terminated strings */
int mystrcmp(const char *s1, const char *s2){
  char *s1_ptr, *s2_ptr;
  int result, done;

  s1_ptr = s1; s2_ptr = s2;

  do {
    done = 1;    /* done in this iteration unless we change our mind */
    if (*s1_ptr == '\0' && *s2_ptr == '\0') 
      result = 0;
    else if (*s1_ptr == '\0' && *s2_ptr != '\0')
      result = -1;
    else if (*s1_ptr != '\0' && *s2_ptr == '\0')
      result = 1;
    else if (*s1_ptr < *s2_ptr)
      result = -1;
    else if (*s1_ptr > *s2_ptr)
      result = 1;
    else{
      s1_ptr++; s2_ptr++; done = 0;
    }
  }
  while (!done);

  return result;
}

void compare(char *s1, char *s2){
  printf("strcmp(\"%s\",\"%s\") = %i, %i\n", s1, s2, mystrcmp(s1,s2), strcmp(s1,s2));
}

int main(void) {

  compare("abe", "kat");
  compare("abe", "abe");
  compare("", "kat");
  compare("", "");
  compare("", "a");
  compare("a", "");
  compare("abe", "aben");
  compare("aben", "aben");
  
  return 0;
}