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