Fix typos: CIRCLE_* -> CIRCLEQ_*
[dragonfly.git] / lib / libc / string / strstr.3
CommitLineData
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1.\" Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org>
2.\" Copyright (c) 1990, 1991, 1993
3.\" The Regents of the University of California. All rights reserved.
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5.\" This code is derived from software contributed to Berkeley by
6.\" Chris Torek and the American National Standards Committee X3,
7.\" on Information Processing Systems.
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37.\" @(#)strstr.3 8.1 (Berkeley) 6/4/93
38.\" $FreeBSD: src/lib/libc/string/strstr.3,v 1.3.2.5 2001/12/25 00:36:53 ache Exp $
52ac7bd7 39.\" $DragonFly: src/lib/libc/string/strstr.3,v 1.4 2004/07/08 00:27:11 hmp Exp $
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40.\"
41.Dd October 11, 2001
42.Dt STRSTR 3
43.Os
44.Sh NAME
45.Nm strstr , strcasestr , strnstr
46.Nd locate a substring in a string
47.Sh LIBRARY
48.Lb libc
49.Sh SYNOPSIS
50.In string.h
51.Ft char *
52.Fn strstr "const char *big" "const char *little"
53.Ft char *
54.Fn strcasestr "const char *big" "const char *little"
55.Ft char *
56.Fn strnstr "const char *big" "const char *little" "size_t len"
57.Sh DESCRIPTION
58The
59.Fn strstr
60function
61locates the first occurrence of the null-terminated string
62.Fa little
63in the null-terminated string
64.Fa big .
65.Pp
66The
67.Fn strcasestr
68function is similar to
69.Fn strstr ,
70but ignores the case of both strings.
71.Pp
72The
73.Fn strnstr
74function
75locates the first occurrence of the null-terminated string
76.Fa little
77in the string
78.Fa big ,
79where not more than
80.Fa len
81characters are searched.
82Characters that appear after a
83.Ql \e0
84character are not searched.
85Since the
86.Fn strnstr
87function is a
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88.Fx
89/
90.Dx
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91specific API, it should only be used when portability is not a concern.
92.Sh RETURN VALUES
93If
94.Fa little
95is an empty string,
96.Fa big
97is returned;
98if
99.Fa little
100occurs nowhere in
101.Fa big ,
102.Dv NULL
103is returned;
104otherwise a pointer to the first character of the first occurrence of
105.Fa little
106is returned.
107.Sh EXAMPLES
108The following sets the pointer
109.Va ptr
110to the
111.Qq Li Bar Baz
112portion of
113.Va largestring :
114.Bd -literal -offset indent
115const char *largestring = "Foo Bar Baz";
116const char *smallstring = "Bar";
117char *ptr;
118
119ptr = strstr(largestring, smallstring);
120.Ed
121.Pp
122The following sets the pointer
123.Va ptr
124to
125.Dv NULL ,
126because only the first 4 characters of
127.Va largestring
128are searched:
129.Bd -literal -offset indent
130const char *largestring = "Foo Bar Baz";
131const char *smallstring = "Bar";
132char *ptr;
133
134ptr = strnstr(largestring, smallstring, 4);
135.Ed
136.Sh SEE ALSO
137.Xr memchr 3 ,
138.Xr strchr 3 ,
139.Xr strcspn 3 ,
140.Xr strpbrk 3 ,
141.Xr strrchr 3 ,
142.Xr strsep 3 ,
143.Xr strspn 3 ,
144.Xr strtok 3
145.Sh STANDARDS
146The
147.Fn strstr
148function
149conforms to
150.St -isoC .