[apple/libc.git] / string / strsep.3

.\" 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
.\" $FreeBSD: src/lib/libc/string/strsep.3,v 1.11 2001/10/01 16:09:00 ru Exp $
.\"
.Dd June 9, 1993
.Dt STRSEP 3
.Os
.Sh NAME
.Nm strsep
.Nd separate strings
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In string.h
.Ft char *
.Fn strsep "char **stringp" "const 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 NULL, if the end of the string was reached) is stored in
.Fa *stringp .
The original value of
.Fa *stringp
is returned.
.Pp
An ``empty'' field, i.e. one caused by two adjacent delimiter characters,
can be detected by comparing the location referenced by the pointer returned
in
.Fa *stringp
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 white space, into an
argument vector:
.Bd -literal -offset indent
char **ap, *argv[10], *inputstring;

for (ap = argv; (*ap = strsep(&inputstring, " \et")) != NULL;)
	if (**ap != '\e0')
		if (++ap >= &argv[10])
			break;
.Ed
.Sh SEE ALSO
.Xr memchr 3 ,
.Xr strchr 3 ,
.Xr strcspn 3 ,
.Xr strpbrk 3 ,
.Xr strrchr 3 ,
.Xr strspn 3 ,
.Xr strstr 3 ,
.Xr strtok 3
.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 -isoC )
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 .
Commit	Line	Data
5b2abdfb	1	.\" Copyright (c) 1990, 1991, 1993
e9ce8d39 A	2	.\" The Regents of the University of California. All rights reserved.
e9ce8d39 A	3	.\"
5b2abdfb A	4	.\" This code is derived from software contributed to Berkeley by
	5	.\" Chris Torek.
	6	.\"
e9ce8d39 A	7	.\" Redistribution and use in source and binary forms, with or without
	8	.\" modification, are permitted provided that the following conditions
	9	.\" are met:
	10	.\" 1. Redistributions of source code must retain the above copyright
	11	.\" notice, this list of conditions and the following disclaimer.
	12	.\" 2. Redistributions in binary form must reproduce the above copyright
	13	.\" notice, this list of conditions and the following disclaimer in the
	14	.\" documentation and/or other materials provided with the distribution.
	15	.\" 3. All advertising materials mentioning features or use of this software
	16	.\" must display the following acknowledgement:
	17	.\" This product includes software developed by the University of
	18	.\" California, Berkeley and its contributors.
	19	.\" 4. Neither the name of the University nor the names of its contributors
	20	.\" may be used to endorse or promote products derived from this software
	21	.\" without specific prior written permission.
	22	.\"
	23	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	24	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	25	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	26	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	27	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	28	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	29	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	30	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	31	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	32	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	33	.\" SUCH DAMAGE.
	34	.\"
5b2abdfb A	35	.\" @(#)strsep.3 8.1 (Berkeley) 6/9/93
5b2abdfb A	36	.\" $FreeBSD: src/lib/libc/string/strsep.3,v 1.11 2001/10/01 16:09:00 ru Exp $
e9ce8d39	37	.\"
5b2abdfb A	38	.Dd June 9, 1993
5b2abdfb A	39	.Dt STRSEP 3
e9ce8d39 A	40	.Os
e9ce8d39 A	41	.Sh NAME
5b2abdfb A	42	.Nm strsep
5b2abdfb A	43	.Nd separate strings
e9ce8d39 A	44	.Sh LIBRARY
	45	.Lb libc
	46	.Sh SYNOPSIS
5b2abdfb A	47	.In string.h
	48	.Ft char *
	49	.Fn strsep "char *stringp" "const char delim"
e9ce8d39 A	50	.Sh DESCRIPTION
e9ce8d39 A	51	The
5b2abdfb A	52	.Fn strsep
	53	function locates, in the string referenced by
	54	.Fa *stringp ,
	55	the first occurrence of any character in the string
	56	.Fa delim
	57	(or the terminating
	58	.Ql \e0
	59	character) and replaces it with a
	60	.Ql \e0 .
	61	The location of the next character after the delimiter character
	62	(or NULL, if the end of the string was reached) is stored in
	63	.Fa *stringp .
	64	The original value of
	65	.Fa *stringp
	66	is returned.
	67	.Pp
	68	An ``empty'' field, i.e. one caused by two adjacent delimiter characters,
	69	can be detected by comparing the location referenced by the pointer returned
	70	in
	71	.Fa *stringp
	72	to
	73	.Ql \e0 .
	74	.Pp
e9ce8d39	75	If
5b2abdfb A	76	.Fa *stringp
	77	is initially
	78	.Dv NULL ,
	79	.Fn strsep
	80	returns
	81	.Dv NULL .
	82	.Sh EXAMPLES
	83	The following uses
	84	.Fn strsep
	85	to parse a string, containing tokens delimited by white space, into an
	86	argument vector:
	87	.Bd -literal -offset indent
	88	char *ap, argv[10], *inputstring;
	89
	90	for (ap = argv; (*ap = strsep(&inputstring, " \et")) != NULL;)
	91	if (**ap != '\e0')
	92	if (++ap >= &argv[10])
	93	break;
e9ce8d39	94	.Ed
e9ce8d39	95	.Sh SEE ALSO
5b2abdfb A	96	.Xr memchr 3 ,
	97	.Xr strchr 3 ,
	98	.Xr strcspn 3 ,
	99	.Xr strpbrk 3 ,
	100	.Xr strrchr 3 ,
	101	.Xr strspn 3 ,
	102	.Xr strstr 3 ,
	103	.Xr strtok 3
e9ce8d39 A	104	.Sh HISTORY
e9ce8d39 A	105	The
5b2abdfb A	106	.Fn strsep
	107	function
	108	is intended as a replacement for the
	109	.Fn strtok
	110	function.
	111	While the
	112	.Fn strtok
	113	function should be preferred for portability reasons (it conforms to
	114	.St -isoC )
	115	it is unable to handle empty fields, i.e. detect fields delimited by
	116	two adjacent delimiter characters, or to be used for more than a single
	117	string at a time.
	118	The
	119	.Fn strsep
e9ce8d39 A	120	function first appeared in
e9ce8d39 A	121	.Bx 4.4 .