freebsd/lib/libc/string/strtok.3

.\" Copyright (c) 1998 Softweyr LLC.  All rights reserved.
.\"
.\" strtok_r, from Berkeley strtok
.\" Oct 13, 1998 by Wes Peters <wes@softweyr.com>
.\"
.\" Copyright (c) 1988, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
.\"
.\" 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
.\"    notices, this list of conditions and the following disclaimer.
.\" 
.\" 2. Redistributions in binary form must reproduce the above
.\"    copyright notices, 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 Softweyr LLC, the
.\"      University of California, Berkeley, and its contributors.
.\"
.\" 4. Neither the name of Softweyr LLC, 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 SOFTWEYR LLC, 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 SOFTWEYR LLC, 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.
.\"
.\"     @(#)strtok.3	8.2 (Berkeley) 2/3/94
.\" $FreeBSD$
.\"
.Dd November 27, 1998
.Dt STRTOK 3
.Os FreeBSD
.Sh NAME
.Nm strtok, strtok_r
.Nd string tokens
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd #include <string.h>
.Ft char *
.Fn strtok "char *str" "const char *sep"
.Ft char *
.Fn strtok_r "char *str" "const char *sep" "char **last"
.Sh DESCRIPTION
.Bf -symbolic
This interface is obsoleted by strsep(3).
.Ef
.Pp
The
.Fn strtok
function
is used to isolate sequential tokens in a null-terminated string,
.Fa str .
These tokens are separated in the string by at least one of the
characters in
.Fa sep .
The first time that
.Fn strtok
is called,
.Fa str
should be specified; subsequent calls, wishing to obtain further tokens
from the same string, should pass a null pointer instead.
The separator string,
.Fa sep ,
must be supplied each time, and may change between calls.
.Pp
The implementation will behave as if no library function calls
.Fn strtok .
.Pp
The
.Fn strtok_r
function is a reentrant version of
.Fn strtok .
The context pointer
.Fa last
must be provided on each call.
.Fn strtok_r
may also be used to nest two parsing loops within one another, as
long as separate context pointers are used.
.Pp
The
.Fn strtok
and
.Fn strtok_r
functions
return a pointer to the beginning of each subsequent token in the string,
after replacing the token itself with a
.Dv NUL
character.
When no more tokens remain, a null pointer is returned.
.Sh EXAMPLES
The following uses
.Fn strtok_r 
to parse two strings using separate contexts:
.Bd -literal
char test[80], blah[80];
char *sep = "\e\e/:;=-";
char *word, *phrase, *brkt, *brkb;

strcpy(test, "This;is.a:test:of=the/string\e\etokenizer-function.");

for (word = strtok_r(test, sep, &brkt);
     word;
     word = strtok_r(NULL, sep, &brkt))
{
    strcpy(blah, "blah:blat:blab:blag");

    for (phrase = strtok_r(blah, sep, &brkb);
         phrase;
         phrase = strtok_r(NULL, sep, &brkb))
    {
        printf("So far we're at %s:%s\en", word, phrase);
    }
}
.Ed
.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
.Sh STANDARDS
The
.Fn strtok
function
conforms to
.St -ansiC .
.Sh BUGS
The System V
.Fn strtok ,
if handed a string containing only delimiter characters,
will not alter the next starting point, so that a call to
.Fn strtok
with a different (or empty) delimiter string
may return a
.Pf non- Dv NULL
value.
Since this implementation always alters the next starting point,
such a sequence of calls would always return
.Dv NULL .
.Sh AUTHORS
.An Wes Peters, Softweyr LLC: Aq wes@softweyr.com
.Pp
Based on the 
.Fx 3.0
implementation.