1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek and the American National Standards Committee X3, 6.\" on Information Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)memcmp.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd June 4, 1993 36.Dt MEMCMP 3 37.Os 38.Sh NAME 39.Nm memcmp 40.Nd compare byte string 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In string.h 45.Ft int 46.Fn memcmp "const void *b1" "const void *b2" "size_t len" 47.Sh DESCRIPTION 48The 49.Fn memcmp 50function 51compares byte string 52.Fa b1 53against byte string 54.Fa b2 . 55Both strings are assumed to be 56.Fa len 57bytes long. 58.Sh RETURN VALUES 59The 60.Fn memcmp 61function 62returns zero if the two strings are identical, 63otherwise returns the difference between the first two differing bytes 64(treated as 65.Vt "unsigned char" 66values, so that 67.Sq Li \e200 68is greater than 69.Sq Li \&\e0 , 70for example). 71Zero-length strings are always identical. 72.Sh SEE ALSO 73.Xr bcmp 3 , 74.Xr strcasecmp 3 , 75.Xr strcmp 3 , 76.Xr strcoll 3 , 77.Xr strxfrm 3 , 78.Xr wmemcmp 3 79.Sh STANDARDS 80The 81.Fn memcmp 82function 83conforms to 84.St -isoC . 85