c strcmp source code

Question

int strcmp(const char *s1, const char *s2)

{
  int ret = 0;

  while (!(ret = *(unsigned char *) s1 - *(unsigned char *) s2) && *s2) ++s1, ++s2;

  if (ret < 0)

    ret = -1;
  else if (ret > 0)

    ret = 1 ;

  return ret;
}

I review the code from : http://www.jbox.dk/sanos/source/lib/string.c.html

I suppose that there're some problem. If strlen(s2)>strlen(s1),then ++s1 may beyond the range. Unfortunately, then the function return error.

Answer 1

No, there's no such problem since the loop continues only while *s1 and *s2 are equal and *s2 is not 0. If s1 is shorter, once it gets to the \0 at the end of s1, the equality condition would break and the loop would stop.

Answer 2

No, there's not such a problem, provided that s2 is '\0'-terminated.