.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
.\"
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.\" Rewritten old page, 960210, aeb@cwi.nl
.\" Updated, added strtok_r. 2000-02-13 Nicolás Lichtmaier <nick@debian.org>
.TH STRTOK 3  "February 13, 2000" "GNU" "Linux Programmer's Manual"
.SH NAME
strtok, strtok_r \- extract tokens from strings
.SH SYNOPSIS
.nf
.B #include <string.h>
.sp
.BI "char *strtok(char *" s ", const char *" delim );
.sp
.BI "char *strtok_r(char *" s ", const char *" delim ", char **" ptrptr );
.fi
.SH DESCRIPTION
A `token' is a nonempty string of characters not occurring in
the string \fIdelim\fP, followed by \e0 or by a character occurring
in \fIdelim\fP.
.PP
The \fBstrtok()\fP function can be used to parse the string \fIs\fP
into tokens. The first call to \fBstrtok()\fP should have \fIs\fP
as its first argument. Subsequent calls should have the first argument
set to NULL. Each call returns a pointer to the next token, or NULL
when no more tokens are found.
.PP
If a token ends with a delimiter, this delimiting character is
overwritten with a \e0 and a pointer to the next character is
saved for the next call to \fBstrtok()\fP.
The delimiter string \fIdelim\fP may be different for each call.
.PP
The 
.B strtok_r()
function works the same as the
.B strtok()
function, but instead of using a static buffer it uses a pointer
to a user allocated char* pointer. This pointer, the
.I ptrptr
parameter, must be the same while parsing the same string.
.SH "BUGS"
Never use these functions. If you do, note that:
.PP
.RS
These functions modify their first argument.
.PP
The identity of the delimiting character is lost.
.PP
These functions cannot be used on constant strings.
.PP
The
.BR strtok ()
function uses a static buffer while parsing, so it's not thread safe. Use
.BR strtok_r ()
if this matters to you.
.RE
.SH "RETURN VALUE"
The \fBstrtok()\fP function returns a pointer to the next token, or
NULL if there are no more tokens.
.SH "CONFORMING TO"
.TP
strtok()
SVID 3, POSIX, BSD 4.3, ISO 9899
.TP
strtok_r()
POSIX.1c
.SH "SEE ALSO"
.BR index "(3), " memchr "(3), " rindex "(3), " strchr (3),
.BR strpbrk "(3), " strsep "(3), " strspn "(3), " strstr (3)