compiler/stdc/strncasecmp.c

   1 /*
   2     Copyright © 1995-2012, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     POSIX.1-2008 function strncasecmp().
   6 */
   7
   8 #include <ctype.h>
   9 /*****************************************************************************
  10
  11     NAME */
  12 #include <string.h>
  13
  14         int strncasecmp (
  15
  16 /*  SYNOPSIS */
  17         const char * str1,
  18         const char * str2,
  19         size_t       n)
  20
  21 /*  FUNCTION
  22         Calculate str1 - str2 ignoring case. Upto n characters are taken
  23         into account.
  24
  25     INPUTS
  26         str1, str2 - Strings to compare
  27
  28     RESULT
  29         The difference of the strings. The difference is 0, if both are
  30         equal, < 0 if str1 < str2 and > 0 if str1 > str2. Note that
  31         it may be greater then 1 or less than -1.
  32
  33     NOTES
  34         This function is not part of a library and may thus be called
  35         any time.
  36
  37     EXAMPLE
  38
  39     BUGS
  40
  41     SEE ALSO
  42
  43     INTERNALS
  44
  45 ******************************************************************************/
  46 {
  47     /*
  48         If n == 0, then this will never be initialized, but is used
  49         later on, so we have to initialize it.
  50     */
  51     int diff = 0;
  52
  53     /* No need to check *str2 since: a) str1 is equal str2 (both are 0),
  54         then *str1 will terminate the loop b) str1 and str2 are not equal
  55         (eg. *str2 is 0), then the diff part will be FALSE. I calculate
  56         the diff first since a) it's more probable that the first chars
  57         will be different and b) I don't need to initialize diff then. */
  58     while (n && !(diff = tolower (*str1) - tolower (*str2)) && *str1)
  59     {
  60         /* advance both strings. I do that here, since doing it in the
  61             check above would mean to advance the strings once too often */
  62         str1 ++;
  63         str2 ++;
  64
  65         n--;
  66     }
  67
  68     /* Now return the difference. */
  69     return diff;
  70 } /* strncasecmp */