libiberty/strncmp.c

   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 #ifdef ANSI_PROTOTYPES
  17 #include <stddef.h>
  18 #else
  19 #define size_t unsigned long
  20 #endif
  21
  22 int
  23 strncmp(s1, s2, n)
  24      const char *s1, *s2;
  25      register size_t n;
  26 {
  27   register unsigned char u1, u2;
  28
  29   while (n-- > 0)
  30     {
  31       u1 = (unsigned char) *s1++;
  32       u2 = (unsigned char) *s2++;
  33       if (u1 != u2)
  34         return u1 - u2;
  35       if (u1 == '\0')
  36         return 0;
  37     }
  38   return 0;
  39 }