strncmp.c   [plain text]


/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1992, 1997 NeXT Software, Inc.  All rights reserved.
 * 
 *	File:	libc/gen/ppc/strncmp.c
 *
 *	This file contains machine dependent code for string comparison
 *
 * HISTORY
 *  24-Jan-1997 Umesh Vaishampayan (umeshv@NeXT.com)
 *	Ported to PPC.
 * 24-Nov-92  Derek B Clegg (dclegg@next.com)
 *	Created.
 */
#import <string.h>

/* This routine should be optimized. */

/* ANSI sez:
 *   The `strncmp' function compares not more than `n' characters (characters
 *   that follow a null character are not compared) from the array pointed to
 *   by `s1' to the array pointed to by `s2'.
 *   The `strncmp' function returns an integer greater than, equal to, or less
 *   than zero, according as 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'.  [4.11.4.4]
 */
int
strncmp(const char *s1, const char *s2, size_t n)
{
    for ( ; n > 0; s1++, s2++, --n)
	if (*s1 != *s2)
	    return ((*(unsigned char *)s1 < *(unsigned char *)s2) ? -1 : +1);
	else if (*s1 == '\0')
	    return 0;
    return 0;
}