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[unix-history] / usr / src / lib / libc / string / strtok.3

.\" Copyright (c) 1988, 1991 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.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)strtok.3    5.8 (Berkeley) %G%
.\"
.Dd 
.Dt STRTOK 3
.Os BSD 3
.Sh NAME
.Nm strtok ,
.Nm strsep
.Nd string token operations
.Sh SYNOPSIS
.Fd #include <string.h>
.Ft char *
.Fn strtok "char *str" "const char *sep"
.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
.Fn strtok
function
returns 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 SEE ALSO
.Xr index 3 ,
.Xr memchr 3 ,
.Xr rindex 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
There is no way to get tokens from multiple strings simultaneously.
.Pp
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 .