xref: /freebsd/lib/libc/string/strtok.3 (revision 5521ff5a4d1929056e7ffc982fac3341ca54df7c)
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 FreeBSD
56.Sh NAME
57.Nm strtok , strtok_r
58.Nd string tokens
59.Sh LIBRARY
60.Lb libc
61.Sh SYNOPSIS
62.Fd #include <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 strsep(3).
70.Ef
71.Pp
72The
73.Fn strtok
74function
75is used to isolate sequential tokens in a null-terminated string,
76.Fa str .
77These tokens are separated in the string by at least one of the
78characters in
79.Fa sep .
80The first time that
81.Fn strtok
82is called,
83.Fa str
84should be specified; subsequent calls, wishing to obtain further tokens
85from the same string, should pass a null pointer instead.
86The separator string,
87.Fa sep ,
88must be supplied each time, and may change between calls.
89.Pp
90The implementation will behave as if no library function calls
91.Fn strtok .
92.Pp
93The
94.Fn strtok_r
95function is a reentrant version of
96.Fn strtok .
97The context pointer
98.Fa last
99must be provided on each call.
100.Fn strtok_r
101may also be used to nest two parsing loops within one another, as
102long as separate context pointers are used.
103.Pp
104The
105.Fn strtok
106and
107.Fn strtok_r
108functions
109return a pointer to the beginning of each subsequent token in the string,
110after replacing the token itself with a
111.Dv NUL
112character.
113When no more tokens remain, a null pointer is returned.
114.Sh EXAMPLES
115The following uses
116.Fn strtok_r
117to parse two strings using separate contexts:
118.Bd -literal
119char test[80], blah[80];
120char *sep = "\e\e/:;=-";
121char *word, *phrase, *brkt, *brkb;
122
123strcpy(test, "This;is.a:test:of=the/string\e\etokenizer-function.");
124
125for (word = strtok_r(test, sep, &brkt);
126     word;
127     word = strtok_r(NULL, sep, &brkt))
128{
129    strcpy(blah, "blah:blat:blab:blag");
130
131    for (phrase = strtok_r(blah, sep, &brkb);
132         phrase;
133         phrase = strtok_r(NULL, sep, &brkb))
134    {
135        printf("So far we're at %s:%s\en", word, phrase);
136    }
137}
138.Ed
139.Sh SEE ALSO
140.Xr memchr 3 ,
141.Xr strchr 3 ,
142.Xr strcspn 3 ,
143.Xr strpbrk 3 ,
144.Xr strrchr 3 ,
145.Xr strsep 3 ,
146.Xr strspn 3 ,
147.Xr strstr 3
148.Sh STANDARDS
149The
150.Fn strtok
151function
152conforms to
153.St -isoC .
154.Sh BUGS
155The System V
156.Fn strtok ,
157if handed a string containing only delimiter characters,
158will not alter the next starting point, so that a call to
159.Fn strtok
160with a different (or empty) delimiter string
161may return a
162.Pf non- Dv NULL
163value.
164Since this implementation always alters the next starting point,
165such a sequence of calls would always return
166.Dv NULL .
167.Sh AUTHORS
168.An Wes Peters ,
169Softweyr LLC:
170.Aq wes@softweyr.com
171.Pp
172Based on the
173.Fx 3.0
174implementation.
175