.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek.
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.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
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.\"    may be used to endorse or promote products derived from this software
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.\"     @(#)index.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dt INDEX 3
.Os
.Sh NAME
.Nm index
.Nd locate character in string
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In strings.h
.Ft char *
.Fn index "const char *s" "int c"
.Sh DESCRIPTION
The
.Fn index
function
locates the first character matching
.Fa c
(converted to a
.Vt char )
in the null-terminated string
.Fa s .
.Sh RETURN VALUES
A pointer to the character is returned if it is found; otherwise
.Dv NULL
is returned.
If
.Fa c
is '\e0',
.Fn index
locates the terminating '\e0'.
.Sh SEE ALSO
.Xr memchr 3 ,
.Xr rindex 3 ,
.Xr strchr 3 ,
.Xr strcspn 3 ,
.Xr strpbrk 3 ,
.Xr strrchr 3 ,
.Xr strsep 3 ,
.Xr strspn 3 ,
.Xr strstr 3 ,
.Xr strtok 3
.Sh HISTORY
A
.Fn index
function appeared in
.At v6 .
Its prototype existed previously in
.Aq Pa string.h
before it was moved to
.Aq Pa strings.h
for
.St -p1003.1-2001
compliance.