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: head/lib/libc/string/memcmp.3 251069 2013-05-28 20:57:40Z emaste $ 34.\" 35.Dd April 7, 2019 36.Dt MEMCMP 3 37.Os 38.Sh NAME 39.Nm memcmp , 40.Nm bcmp 41.Nd compare byte string 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In string.h 46.Ft int 47.Fn memcmp "const void *b1" "const void *b2" "size_t len" 48.Ft int 49.Fn bcmp "const void *b1" "const void *b2" "size_t len" 50.Sh DESCRIPTION 51The 52.Fn memcmp 53and 54.Fn bcmp 55functions 56compare byte string 57.Fa b1 58against byte string 59.Fa b2 . 60Both strings are assumed to be 61.Fa len 62bytes long. 63.Sh RETURN VALUES 64The 65.Fn memcmp 66and 67.Fn bcmp 68functions 69return zero if the two strings are identical, 70otherwise return the difference between the first two differing bytes 71(treated as 72.Vt "unsigned char" 73values, so that 74.Sq Li \e200 75is greater than 76.Sq Li \&\e0 , 77for example). 78Zero-length strings are always identical. 79.Sh SEE ALSO 80.Xr strcasecmp 3 , 81.Xr strcmp 3 , 82.Xr strcoll 3 , 83.Xr strxfrm 3 , 84.Xr wmemcmp 3 85.Sh STANDARDS 86The 87.Fn memcmp 88function 89conforms to 90.St -isoC . 91.Pp 92A 93.Fn bcmp 94function first appeared in 95.Bx 4.2 . 96Its prototype existed previously in 97.In string.h 98before it was moved to 99.In strings.h 100for 101.St -p1003.1-2001 102compliance. 103