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