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.\" @(#)memchr.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd April 9, 2008 36.Dt MEMCHR 3 37.Os 38.Sh NAME 39.Nm memchr 40.Nd locate byte in byte string 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In string.h 45.Ft void * 46.Fn memchr "const void *b" "int c" "size_t len" 47.Ft void * 48.Fn memrchr "const void *b" "int c" "size_t len" 49.Sh DESCRIPTION 50The 51.Fn memchr 52function 53locates the first occurrence of 54.Fa c 55(converted to an 56.Vt "unsigned char" ) 57in string 58.Fa b . 59.Pp 60The 61.Fn memrchr 62function behaves like 63.Fn memchr , 64except that it locates the last occurrence of 65.Fa c 66in string 67.Fa b . 68.Sh RETURN VALUES 69The 70.Fn memchr 71and 72.Fn memrchr 73functions 74return a pointer to the byte located, 75or NULL if no such byte exists within 76.Fa len 77bytes. 78.Sh SEE ALSO 79.Xr memmem 3 , 80.Xr strchr 3 , 81.Xr strcspn 3 , 82.Xr strpbrk 3 , 83.Xr strrchr 3 , 84.Xr strsep 3 , 85.Xr strspn 3 , 86.Xr strstr 3 , 87.Xr strtok 3 , 88.Xr wmemchr 3 89.Sh STANDARDS 90The 91.Fn memchr 92function 93conforms to 94.St -isoC . 95.Pp 96The 97.Fn memrchr 98function is a GNU extension and conforms to no standard. 99.Sh HISTORY 100The 101.Fn memrchr 102function first appeared in GNU libc 2.1.91, this implementation 103first appeared in 104.Fx 6.4 , 105coming from 106.Ox 4.3 . 107