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4.\" This code is derived from software contributed to Berkeley by
5.\" Chris Torek.
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31.\"     from: @(#)strsep.3	8.1 (Berkeley) 6/9/93
32.\"	$NetBSD: strsep.3,v 1.19 2006/10/16 08:48:45 wiz Exp $
33.\"
34.Dd August 12, 2006
35.Dt STRSEP 3
36.Os
37.Sh NAME
38.Nm strsep ,
39.Nm stresep
40.Nd separate strings
41.Sh LIBRARY
42.Lb libc
43.Sh SYNOPSIS
44.In string.h
45.Ft char *
46.Fn strsep "char **stringp" "const char *delim"
47.Ft char *
48.Fn stresep "char **stringp" "const char *delim" "int escape"
49.Sh DESCRIPTION
50The
51.Fn strsep
52function locates, in the nul-terminated string referenced by
53.Fa *stringp ,
54the first occurrence of any character in the string
55.Fa delim
56(or the terminating
57.Ql \e0
58character) and replaces it with a
59.Ql \e0 .
60The location of the next character after the delimiter character
61(or
62.Dv NULL ,
63if the end of the string was reached) is stored in
64.Fa *stringp .
65The original value of
66.Fa *stringp
67is returned.
68.Pp
69An
70.Dq empty
71field, i.e., one caused by two adjacent delimiter characters,
72can be detected by comparing the location referenced by the pointer returned
73by
74.Fn strsep
75to
76.Ql \e0 .
77.Pp
78If
79.Fa *stringp
80is initially
81.Dv NULL ,
82.Fn strsep
83returns
84.Dv NULL .
85The
86.Fn stresep
87function also takes an escape character that allows quoting the delimiter
88character so that it can be part of the source string.
89.Sh EXAMPLES
90The following uses
91.Fn strsep
92to parse a string, containing tokens delimited by white space, into an
93argument vector:
94.Bd -literal -offset indent
95char **ap, *argv[10], *inputstring;
96
97for (ap = argv; ap \*[Lt] \*[Am]argv[9] \*[Am]\*[Am]
98    (*ap = strsep(\*[Am]inputstring, " \et")) != NULL;) {
99	if (**ap != '\e0')
100		ap++;
101}
102.Ed
103.Sh HISTORY
104The
105.Fn strsep
106function
107is intended as a replacement for the
108.Fn strtok
109function.
110While the
111.Fn strtok
112function should be preferred for portability reasons (it conforms to
113.St -ansiC )
114it is unable to handle empty fields, i.e., detect fields delimited by
115two adjacent delimiter characters, or to be used for more than a single
116string at a time.
117The
118.Fn strsep
119function first appeared in
120.Bx 4.4 .
121