wcsncmp.c

cygwin, 著名的在win32下模拟unix操作系统的东东

/*
FUNCTION
	<<wcsncmp>>---compare part of two wide-character strings 

ANSI_SYNOPSIS
	#include <wchar.h>
	int wcsncmp(const wchar_t *<[s1]>, const wchar_t *<[s2]>, size_t <[n]>);

TRAD_SYNOPSIS
	int wcsncmp(<[s1]>, <[s2]>, <[n]>
	const wchar_t *<[s1]>;
	const wchar_t *<[s2]>;
	size_t <[n]>;

DESCRIPTION
	The <<wcsncmp>> function compares not more than <[n]> wide-character
	codes (wide-character codes that follow a null wide-character code are
	not compared) from the array pointed to by <[s1]> to the array pointed
	to by <[s2]>.

	The sign of a non-zero return value is determined by the sign of the
	difference between the values of the first pair of wide-character codes
	that differ in the objects being compared. 

RETURNS
	Upon successful completion, <<wcsncmp>> returns an integer greater than,
	equal to or less than 0, if the possibly null-terminated array pointed
	to by <[s1]> is greater than, equal to or less than the possibly
	null-terminated array pointed to by <[s2]> respectively. 

PORTABILITY
<<wcsncmp>> is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
*/

/*	$NetBSD$	*/

/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <_ansi.h>
#include <wchar.h>

int
_DEFUN (wcsncmp, (s1, s2, n),
	_CONST wchar_t * s1 _AND
	_CONST wchar_t * s2 _AND
	size_t n)
{

  if (n == 0)
    return (0);
  do
    {
      if (*s1 != *s2++)
	{
	  return (*s1 - *--s2);
	}
      if (*s1++ == 0)
	break;
    }
  while (--n != 0);
  return (0);
}