strncmp.c

来自「操作系统源代码」· C语言 代码 · 共 27 行

/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* $Id: strncmp.c,v 1.4 1994/06/24 11:57:04 ceriel Exp $ */

#include	<string.h>

int
strncmp(register const char *s1, register const char *s2, register size_t n)
{
	if (n) {
		do {
			if (*s1 != *s2++)
				break;
			if (*s1++ == '\0')
				return 0;
		} while (--n > 0);
		if (n > 0) {
			if (*s1 == '\0') return -1;
			if (*--s2 == '\0') return 1;
			return (unsigned char) *s1 - (unsigned char) *s2;
		}
	}
	return 0;
}