sysdeps/generic/strcasecmp.c

   1 /* Copyright (C) 1991, 1992, 1995 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 Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 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 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <string.h>
  20 #include <ctype.h>
  21
  22 /* Compare S1 and S2, ignoring case, returning less than, equal to or
  23    greater than zero if S1 is lexiographically less than,
  24    equal to or greater than S2.  */
  25 int
  26 __strcasecmp (const char *s1, const char *s2)
  27 {
  28   register const unsigned char *p1 = (const unsigned char *) s1;
  29   register const unsigned char *p2 = (const unsigned char *) s2;
  30   unsigned char c1, c2;
  31
  32   if (p1 == p2)
  33     return 0;
  34
  35   do
  36     {
  37       c1 = tolower (*p1++);
  38       c2 = tolower (*p2++);
  39       if (c1 == '\0')
  40         break;
  41     }
  42   while (c1 == c2);
  43
  44   return c1 - c2;
  45 }
  46 weak_alias (__strcasecmp, strcasecmp)