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.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek.
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.\"     @(#)index.3	8.1 (Berkeley) 6/4/93
.\"
.Dd March 20, 2011
.Dt INDEX 3
.Os
.Sh NAME
.Nm index , rindex
.Nd locate character in string
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In strings.h
.Ft "char *"
.Fn index "const char *s" "int c"
.Ft "char *"
.Fn rindex "const char *s" "int c"
.Sh DESCRIPTION
.Bf -symbolic
The
.Fn index
and
.Fn rindex
functions have been deprecated in favor of
.Xr strchr 3
and
.Xr strrchr 3 .
.Ef
.Pp
The
.Fn index
function
locates the first occurrence of
.Fa c
(converted to a
.Vt char )
in the string pointed to by
.Fa s .
The terminating null character is considered part of the string;
therefore if
.Fa c
is
.Ql \e0 ,
the functions locate the terminating
.Ql \e0 .
.Pp
The
.Fn rindex
function is identical to
.Fn index ,
except it locates the last occurrence of
.Fa c .
.Sh RETURN VALUES
The functions
.Fn index
and
.Fn rindex
return a pointer to the located character, or
.Dv NULL
if the character does not appear in the string.
.Sh SEE ALSO
.Xr memchr 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
The
.Fn index
and
.Fn rindex
functions appeared in
.At v6 .
Their prototypes existed previously in
.In string.h
before they were moved to
.In strings.h
for
.St -p1003.1-2001
compliance.
The functions are not specified by
.St -p1003.1-2008 .