1/* strncmp -- compare two strings, stop after n bytes.
2   This function is in the public domain.  */
3
4/*
5
6@deftypefn Supplemental int strncmp (const char *@var{s1}, @
7  const char *@var{s2}, size_t @var{n})
8
9Compares the first @var{n} bytes of two strings, returning a value as
10@code{strcmp}.
11
12@end deftypefn
13
14*/
15
16#include <ansidecl.h>
17#include <stddef.h>
18
19int
20strncmp(const char *s1, const char *s2, register size_t n)
21{
22  register unsigned char u1, u2;
23
24  while (n-- > 0)
25    {
26      u1 = (unsigned char) *s1++;
27      u2 = (unsigned char) *s2++;
28      if (u1 != u2)
29	return u1 - u2;
30      if (u1 == '\0')
31	return 0;
32    }
33  return 0;
34}
35