compiler/stdc/strcmp.c

   1 /*
   2     Copyright © 1995-2012, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     C99 function strcmp().
   6 */
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11 #include <string.h>
  12
  13         int strcmp (
  14
  15 /*  SYNOPSIS */
  16         const char * str1,
  17         const char * str2)
  18
  19 /*  FUNCTION
  20         Calculate str1 - str2.
  21
  22     INPUTS
  23         str1, str2 - Strings to compare
  24
  25     RESULT
  26         The difference of the strings. The difference is 0, if both are
  27         equal, < 0 if str1 < str2 and > 0 if str1 > str2. Note that
  28         it may be greater then 1 or less than -1.
  29
  30     NOTES
  31         This function is not part of a library and may thus be called
  32         any time.
  33
  34     EXAMPLE
  35
  36     BUGS
  37
  38     SEE ALSO
  39
  40     INTERNALS
  41
  42 ******************************************************************************/
  43 {
  44     int diff;
  45
  46     /* No need to check *str2 since: a) str1 is equal str2 (both are 0),
  47         then *str1 will terminate the loop b) str1 and str2 are not equal
  48         (eg. *str2 is 0), then the diff part will be FALSE. I calculate
  49         the diff first since a) it's more probable that the first chars
  50         will be different and b) I don't need to initialize diff then. */
  51     while (!(diff = *(unsigned char*) str1 - *(unsigned char*) str2) && *str1)
  52     {
  53         /* advance both strings. I do that here, since doing it in the
  54             check above would mean to advance the strings once too often */
  55         str1 ++;
  56         str2 ++;
  57     }
  58
  59     /* Now return the difference. */
  60     return diff;
  61 } /* strcmp */
  62