toolchain/gcc/newlib/libc/string/strcasecmp.c

   1 /*
   2 FUNCTION
   3         <<strcasecmp>>---case insensitive character string compare
   4
   5 INDEX
   6         strcasecmp
   7
   8 ANSI_SYNOPSIS
   9         #include <string.h>
  10         int strcasecmp(const char *<[a]>, const char *<[b]>);
  11
  12 TRAD_SYNOPSIS
  13         #include <string.h>
  14         int strcasecmp(<[a]>, <[b]>)
  15         char *<[a]>;
  16         char *<[b]>;
  17
  18 DESCRIPTION
  19         <<strcasecmp>> compares the string at <[a]> to
  20         the string at <[b]> in a case-insensitive manner.
  21
  22 RETURNS
  23
  24         If <<*<[a]>>> sorts lexicographically after <<*<[b]>>> (after
  25         both are converted to upper case), <<strcasecmp>> returns a
  26         number greater than zero.  If the two strings match,
  27         <<strcasecmp>> returns zero.  If <<*<[a]>>> sorts
  28         lexicographically before <<*<[b]>>>, <<strcasecmp>> returns a
  29         number less than zero.
  30
  31 PORTABILITY
  32 <<strcasecmp>> is in the Berkeley Software Distribution.
  33
  34 <<strcasecmp>> requires no supporting OS subroutines. It uses
  35 tolower() from elsewhere in this library.
  36
  37 QUICKREF
  38         strcasecmp
  39 */
  40
  41 #include <string.h>
  42 #include <ctype.h>
  43
  44 int
  45 _DEFUN (strcasecmp, (s1, s2),
  46         _CONST char *s1 _AND
  47         _CONST char *s2)
  48 {
  49   while (*s1 != '\0' && tolower(*s1) == tolower(*s2))
  50     {
  51       s1++;
  52       s2++;
  53     }
  54
  55   return tolower(*(unsigned char *) s1) - tolower(*(unsigned char *) s2);
  56 }