1.\" $OpenBSD: memchr.3,v 1.13 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 MEMCHR 3 36.Os 37.Sh NAME 38.Nm memchr , 39.Nm memrchr 40.Nd locate byte in byte string 41.Sh SYNOPSIS 42.In string.h 43.Ft void * 44.Fn memchr "const void *b" "int c" "size_t len" 45.Ft void * 46.Fn memrchr "const void *b" "int c" "size_t len" 47.Sh DESCRIPTION 48The 49.Fn memchr 50function locates the first occurrence of 51.Fa c 52(converted to an 53.Vt unsigned char ) 54in string 55.Fa b . 56.Pp 57The 58.Fn memrchr 59function behaves like 60.Fn memchr , 61except that it locates the last occurrence of 62.Fa c 63in string 64.Fa b . 65.Sh RETURN VALUES 66The 67.Fn memchr 68and 69.Fn memrchr 70functions return a pointer to the byte located, or 71.Dv NULL 72if no such byte exists within 73.Fa len 74bytes. 75.Sh SEE ALSO 76.Xr strchr 3 , 77.Xr strcspn 3 , 78.Xr strpbrk 3 , 79.Xr strrchr 3 , 80.Xr strsep 3 , 81.Xr strspn 3 , 82.Xr strstr 3 , 83.Xr strtok 3 , 84.Xr wmemchr 3 85.Sh STANDARDS 86The 87.Fn memchr 88function conforms to 89.St -ansiC . 90.Pp 91The 92.Fn memrchr 93function is an 94.Ox 95extension. 96.Sh HISTORY 97The 98.Fn memchr 99function first appeared in 100.At V 101and was reimplemented for 102.Bx 4.3 Tahoe . 103