xref: /netbsd-src/lib/libc/string/strsep.3 (revision 23c8222edbfb0f0932d88a8351d3a0cf817dfb9e)
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31.\"     from: @(#)strsep.3	8.1 (Berkeley) 6/9/93
32.\"	$NetBSD: strsep.3,v 1.16 2004/04/13 23:03:22 wiz Exp $
33.\"
34.Dd August 11, 2002
35.Dt STRSEP 3
36.Os
37.Sh NAME
38.Nm strsep
39.Nd separate strings
40.Sh LIBRARY
41.Lb libc
42.Sh SYNOPSIS
43.In string.h
44.Ft char *
45.Fn strsep "char **stringp" "const char *delim"
46.Sh DESCRIPTION
47The
48.Fn strsep
49function locates, in the null-terminated string referenced by
50.Fa *stringp ,
51the first occurrence of any character in the string
52.Fa delim
53(or the terminating
54.Ql \e0
55character) and replaces it with a
56.Ql \e0 .
57The location of the next character after the delimiter character
58(or
59.Dv NULL ,
60if the end of the string was reached) is stored in
61.Fa *stringp .
62The original value of
63.Fa *stringp
64is returned.
65.Pp
66An
67.Dq empty
68field, i.e., one caused by two adjacent delimiter characters,
69can be detected by comparing the location referenced by the pointer returned
70by
71.Fn strsep
72to
73.Ql \e0 .
74.Pp
75If
76.Fa *stringp
77is initially
78.Dv NULL ,
79.Fn strsep
80returns
81.Dv NULL .
82.Sh EXAMPLES
83The following uses
84.Fn strsep
85to parse a string, containing tokens delimited by white space, into an
86argument vector:
87.Bd -literal -offset indent
88char **ap, *argv[10], *inputstring;
89
90for (ap = argv; ap < \*[Am]argv[9] \*[Am]\*[Am]
91    (*ap = strsep(\*[Am]inputstring, " \et")) != NULL;) {
92	if (**ap != '\e0')
93		ap++;
94}
95.Ed
96.Sh HISTORY
97The
98.Fn strsep
99function
100is intended as a replacement for the
101.Fn strtok
102function.
103While the
104.Fn strtok
105function should be preferred for portability reasons (it conforms to
106.St -ansiC )
107it is unable to handle empty fields, i.e., detect fields delimited by
108two adjacent delimiter characters, or to be used for more than a single
109string at a time.
110The
111.Fn strsep
112function first appeared in
113.Bx 4.4 .
114