.\"	$OpenBSD: memcmp.3,v 1.8 2013/06/05 03:39:23 tedu Exp $
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.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
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.Dd $Mdocdate: June 5 2013 $
.Dt MEMCMP 3
.Os
.Sh NAME
.Nm memcmp
.Nd compare byte string
.Sh SYNOPSIS
.In string.h
.Ft int
.Fn memcmp "const void *b1" "const void *b2" "size_t len"
.Sh DESCRIPTION
The
.Fn memcmp
function compares byte string
.Fa b1
against byte string
.Fa b2 .
Both strings are assumed to be
.Fa len
bytes long.
.Sh RETURN VALUES
The
.Fn memcmp
function returns zero if the two strings are identical,
otherwise returns the difference between the first two differing bytes
(treated as
.Li unsigned char
values, so that
.Sq Li \e200
is greater than
.Sq Li \&\e0 ,
for example).
Zero-length strings are always identical.
.Sh SEE ALSO
.Xr bcmp 3 ,
.Xr strcasecmp 3 ,
.Xr strcmp 3 ,
.Xr strcoll 3 ,
.Xr strxfrm 3 ,
.Xr wmemcmp 3
.Sh STANDARDS
The
.Fn memcmp
function conforms to
.St -ansiC .
.Sh HISTORY
The
.Fn memcmp
function first appeared in
.At V
and was reimplemented for
.Bx 4.3 Tahoe .