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.\" 4. 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.\" $FreeBSD$ 32.\" 33.Dd June 4, 1993 34.Dt INDEX 3 35.Os 36.Sh NAME 37.Nm index , rindex 38.Nd locate character in string 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In strings.h 43.Ft "char *" 44.Fn index "const char *s" "int c" 45.Ft "char *" 46.Fn rindex "const char *s" "int c" 47.Sh DESCRIPTION 48The 49.Fn index 50function 51locates the first occurrence of 52.Fa c 53(converted to a 54.Vt char ) 55in the string pointed to by 56.Fa s . 57The terminating null character is considered part of the string; 58therefore if 59.Fa c 60is 61.Ql \e0 , 62the functions locate the terminating 63.Ql \e0 . 64.Pp 65The 66.Fn rindex 67function is identical to 68.Fn index , 69except it locates the last occurrence of 70.Fa c . 71.Sh RETURN VALUES 72The functions 73.Fn index 74and 75.Fn rindex 76return a pointer to the located character, or 77.Dv NULL 78if the character does not appear in the string. 79.Sh SEE ALSO 80.Xr memchr 3 , 81.Xr strchr 3 , 82.Xr strcspn 3 , 83.Xr strpbrk 3 , 84.Xr strrchr 3 , 85.Xr strsep 3 , 86.Xr strspn 3 , 87.Xr strstr 3 , 88.Xr strtok 3 89.Sh HISTORY 90The 91.Fn index 92and 93.Fn rindex 94functions appeared in 95.At v6 . 96Their prototypes existed previously in 97.In string.h 98before they were moved to 99.In strings.h 100for 101.St -p1003.1-2001 102compliance. 103