xref: /freebsd/lib/libc/string/strtok.3 (revision 6990ffd8a95caaba6858ad44ff1b3157d1efba8f)
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.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
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.
101.Fn strtok_r
102may also be used to nest two parsing loops within one another, as
103long as separate context pointers are used.
104.Pp
105The
106.Fn strtok
107and
108.Fn strtok_r
109functions
110return a pointer to the beginning of each subsequent token in the string,
111after replacing the token itself with a
112.Dv NUL
113character.
114When no more tokens remain, a null pointer is returned.
115.Sh EXAMPLES
116The following uses
117.Fn strtok_r
118to parse two strings using separate contexts:
119.Bd -literal
120char test[80], blah[80];
121char *sep = "\e\e/:;=-";
122char *word, *phrase, *brkt, *brkb;
123
124strcpy(test, "This;is.a:test:of=the/string\e\etokenizer-function.");
125
126for (word = strtok_r(test, sep, &brkt);
127     word;
128     word = strtok_r(NULL, sep, &brkt))
129{
130    strcpy(blah, "blah:blat:blab:blag");
131
132    for (phrase = strtok_r(blah, sep, &brkb);
133         phrase;
134         phrase = strtok_r(NULL, sep, &brkb))
135    {
136        printf("So far we're at %s:%s\en", word, phrase);
137    }
138}
139.Ed
140.Sh SEE ALSO
141.Xr memchr 3 ,
142.Xr strchr 3 ,
143.Xr strcspn 3 ,
144.Xr strpbrk 3 ,
145.Xr strrchr 3 ,
146.Xr strsep 3 ,
147.Xr strspn 3 ,
148.Xr strstr 3
149.Sh STANDARDS
150The
151.Fn strtok
152function
153conforms to
154.St -isoC .
155.Sh BUGS
156The System V
157.Fn strtok ,
158if handed a string containing only delimiter characters,
159will not alter the next starting point, so that a call to
160.Fn strtok
161with a different (or empty) delimiter string
162may return a
163.Pf non- Dv NULL
164value.
165Since this implementation always alters the next starting point,
166such a sequence of calls would always return
167.Dv NULL .
168.Sh AUTHORS
169.An Wes Peters ,
170Softweyr LLC:
171.Aq wes@softweyr.com
172.Pp
173Based on the
174.Fx 3.0
175implementation.
176