.\" $OpenBSD: strsep.3,v 1.8 2000/04/21 15:24:20 aaron Exp $
.\"
.\" 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.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)strsep.3	8.1 (Berkeley) 6/9/93
.\"
.Dd June 9, 1993
.Dt STRSEP 3
.Os
.Sh NAME
.Nm strsep
.Nd separate strings
.Sh SYNOPSIS
.Fd #include <string.h>
.Ft char *
.Fn strsep "char **stringp" "char *delim"
.Sh DESCRIPTION
The
.Fn strsep
function locates, in the string referenced by
.Fa *stringp ,
the first occurrence of any character in the string
.Fa delim
(or the terminating
.Ql \e0
character) and replaces it with a
.Ql \e0 .
The location of the next character after the delimiter character
(or
.Dv NULL ,
if the end of the string was reached) is stored in
.Fa *stringp .
The original value of
.Fa *stringp
is returned.
.Pp
An
.Dq empty
field, i.e., one caused by two adjacent delimiter characters,
can be detected by comparing the location referenced by the pointer returned
by
.Fn strsep
to
.Ql \e0 .
.Pp
If
.Fa *stringp
is initially
.Dv NULL ,
.Fn strsep
returns
.Dv NULL .
.Sh EXAMPLES
The following uses
.Fn strsep
to parse a string, containing tokens delimited by whitespace, into an
argument vector:
.Bd -literal -offset indent
char **ap, *argv[10], *inputstring;

for (ap = argv; (*ap = strsep(&inputstring, " \et")) != NULL;)
	if (**ap != '\e0')
		++ap;
.Ed
.Sh HISTORY
The
.Fn strsep
function is intended as a replacement for the
.Fn strtok
function.
While the
.Fn strtok
function should be preferred for portability reasons (it conforms to
.St -ansiC )
it is unable to handle empty fields, i.e., detect fields delimited by
two adjacent delimiter characters, or to be used for more than a single
string at a time.
The
.Fn strsep
function first appeared in
.Bx 4.4 .