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. 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)index.3 8.1 (Berkeley) 6/4/93 31.\" $FreeBSD: src/lib/libc/string/index.3,v 1.12 2007/01/09 00:28:12 imp Exp $ 32.\" $DragonFly: src/lib/libc/string/index.3,v 1.2 2003/06/17 04:26:46 dillon Exp $ 33.\" 34.Dd June 4, 1993 35.Dt INDEX 3 36.Os 37.Sh NAME 38.Nm index , 39.Nm rindex 40.Nd locate character in string 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In strings.h 45.Ft "char *" 46.Fn index "const char *s" "int c" 47.Ft "char *" 48.Fn rindex "const char *s" "int c" 49.Sh DESCRIPTION 50The 51.Fn index 52function 53locates the first occurrence of 54.Fa c 55(converted to a 56.Vt char ) 57in the string pointed to by 58.Fa s . 59The terminating null character is considered part of the string; 60therefore if 61.Fa c 62is 63.Ql \e0 , 64the functions locate the terminating 65.Ql \e0 . 66.Pp 67The 68.Fn rindex 69function is identical to 70.Fn index , 71except it locates the last occurrence of 72.Fa c . 73.Sh RETURN VALUES 74The functions 75.Fn index 76and 77.Fn rindex 78return a pointer to the located character, or 79.Dv NULL 80if the character does not appear in the string. 81.Sh SEE ALSO 82.Xr memchr 3 , 83.Xr strchr 3 , 84.Xr strcspn 3 , 85.Xr strpbrk 3 , 86.Xr strrchr 3 , 87.Xr strsep 3 , 88.Xr strspn 3 , 89.Xr strstr 3 , 90.Xr strtok 3 91.Sh HISTORY 92The 93.Fn index 94and 95.Fn rindex 96functions appeared in 97.At v6 . 98Their prototypes existed previously in 99.In string.h 100before they were moved to 101.In strings.h 102for 103.St -p1003.1-2001 104compliance. 105