string/strcmp.c

   1 /* Copyright (C) 1991, 1996, 1997, 2003 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <string.h>
  19 #include <memcopy.h>
  20
  21 #undef strcmp
  22
  23 /* Compare S1 and S2, returning less than, equal to or
  24    greater than zero if S1 is lexicographically less than,
  25    equal to or greater than S2.  */
  26 int
  27 strcmp (p1, p2)
  28      const char *p1;
  29      const char *p2;
  30 {
  31   register const unsigned char *s1 = (const unsigned char *) p1;
  32   register const unsigned char *s2 = (const unsigned char *) p2;
  33   unsigned char c1, c2;
  34
  35   do
  36     {
  37       c1 = (unsigned char) *s1++;
  38       c2 = (unsigned char) *s2++;
  39       if (c1 == '\0')
  40         return c1 - c2;
  41     }
  42   while (c1 == c2);
  43
  44   return c1 - c2;
  45 }
  46 libc_hidden_builtin_def (strcmp)