xref: /freebsd/lib/libc/string/strtok.3 (revision f0adf7f5cdd241db2f2c817683191a6ef64a4e95)
1.\" Copyright (c) 1998 Softweyr LLC.  All rights reserved.
2.\"
3.\" strtok_r, from Berkeley strtok
4.\" Oct 13, 1998 by Wes Peters <wes@softweyr.com>
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50.\"     @(#)strtok.3	8.2 (Berkeley) 2/3/94
51.\" $FreeBSD$
52.\"
53.Dd November 27, 1998
54.Dt STRTOK 3
55.Os
56.Sh NAME
57.Nm strtok , strtok_r
58.Nd string tokens
59.Sh LIBRARY
60.Lb libc
61.Sh SYNOPSIS
62.In string.h
63.Ft char *
64.Fn strtok "char *str" "const char *sep"
65.Ft char *
66.Fn strtok_r "char *str" "const char *sep" "char **last"
67.Sh DESCRIPTION
68.Bf -symbolic
69This interface is obsoleted by
70.Xr strsep 3 .
71.Ef
72.Pp
73The
74.Fn strtok
75function
76is used to isolate sequential tokens in a null-terminated string,
77.Fa str .
78These tokens are separated in the string by at least one of the
79characters in
80.Fa sep .
81The first time that
82.Fn strtok
83is called,
84.Fa str
85should be specified; subsequent calls, wishing to obtain further tokens
86from the same string, should pass a null pointer instead.
87The separator string,
88.Fa sep ,
89must be supplied each time, and may change between calls.
90.Pp
91The implementation will behave as if no library function calls
92.Fn strtok .
93.Pp
94The
95.Fn strtok_r
96function is a reentrant version of
97.Fn strtok .
98The context pointer
99.Fa last
100must be provided on each call.
101The
102.Fn strtok_r
103function
104may also be used to nest two parsing loops within one another, as
105long as separate context pointers are used.
106.Pp
107The
108.Fn strtok
109and
110.Fn strtok_r
111functions
112return a pointer to the beginning of each subsequent token in the string,
113after replacing the token itself with a
114.Dv NUL
115character.
116When no more tokens remain, a null pointer is returned.
117.Sh EXAMPLES
118The following uses
119.Fn strtok_r
120to parse two strings using separate contexts:
121.Bd -literal
122char test[80], blah[80];
123char *sep = "\e\e/:;=-";
124char *word, *phrase, *brkt, *brkb;
125
126strcpy(test, "This;is.a:test:of=the/string\e\etokenizer-function.");
127
128for (word = strtok_r(test, sep, &brkt);
129     word;
130     word = strtok_r(NULL, sep, &brkt))
131{
132    strcpy(blah, "blah:blat:blab:blag");
133
134    for (phrase = strtok_r(blah, sep, &brkb);
135         phrase;
136         phrase = strtok_r(NULL, sep, &brkb))
137    {
138        printf("So far we're at %s:%s\en", word, phrase);
139    }
140}
141.Ed
142.Sh SEE ALSO
143.Xr memchr 3 ,
144.Xr strchr 3 ,
145.Xr strcspn 3 ,
146.Xr strpbrk 3 ,
147.Xr strrchr 3 ,
148.Xr strsep 3 ,
149.Xr strspn 3 ,
150.Xr strstr 3 ,
151.Xr wcstok 3
152.Sh STANDARDS
153The
154.Fn strtok
155function
156conforms to
157.St -isoC .
158.Sh BUGS
159The System V
160.Fn strtok ,
161if handed a string containing only delimiter characters,
162will not alter the next starting point, so that a call to
163.Fn strtok
164with a different (or empty) delimiter string
165may return a
166.Pf non- Dv NULL
167value.
168Since this implementation always alters the next starting point,
169such a sequence of calls would always return
170.Dv NULL .
171.Sh AUTHORS
172.An Wes Peters ,
173Softweyr LLC:
174.Aq wes@softweyr.com
175.Pp
176Based on the
177.Fx 3.0
178implementation.
179