1.\" $OpenBSD: memset.3,v 1.9 2022/09/11 06:38:11 jmc Exp $ 2.\" 3.\" Copyright (c) 1990, 1991 The Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Chris Torek and the American National Standards Committee X3, 8.\" on Information Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.Dd $Mdocdate: September 11 2022 $ 35.Dt MEMSET 3 36.Os 37.Sh NAME 38.Nm memset 39.Nd write a byte to byte string 40.Sh SYNOPSIS 41.In string.h 42.Ft void * 43.Fn memset "void *b" "int c" "size_t len" 44.Sh DESCRIPTION 45The 46.Fn memset 47function writes 48.Fa len 49bytes of value 50.Fa c 51(converted to an 52.Vt unsigned char ) 53to the string 54.Fa b . 55.Sh RETURN VALUES 56The 57.Fn memset 58function returns the original value of 59.Fa b . 60.Sh SEE ALSO 61.Xr bzero 3 , 62.Xr swab 3 , 63.Xr wmemset 3 64.Sh STANDARDS 65The 66.Fn memset 67function conforms to 68.St -ansiC . 69.Sh HISTORY 70The 71.Fn memset 72function first appeared in 73.At V 74and was reimplemented for 75.Bx 4.3 Tahoe . 76