Add a bunch of .Fx (FreeBSD) version numbers.
[dragonfly.git] / lib / libc / string / strstr.3
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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.
4.\"
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.
8.\"
9.\" Redistribution and use in source and binary forms, with or without
10.\" modification, are permitted provided that the following conditions
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12.\" 1. Redistributions of source code must retain the above copyright
13.\" notice, this list of conditions and the following disclaimer.
14.\" 2. Redistributions in binary form must reproduce the above copyright
15.\" notice, this list of conditions and the following disclaimer in the
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17.\" 3. All advertising materials mentioning features or use of this software
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19.\" This product includes software developed by the University of
20.\" California, Berkeley and its contributors.
21.\" 4. Neither the name of the University nor the names of its contributors
22.\" may be used to endorse or promote products derived from this software
23.\" without specific prior written permission.
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25.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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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 $
9bb2a92d 39.\" $DragonFly: src/lib/libc/string/strstr.3,v 1.3 2004/03/11 12:28:50 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
9bb2a92d 88.Fx / Dx
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89specific API, it should only be used when portability is not a concern.
90.Sh RETURN VALUES
91If
92.Fa little
93is an empty string,
94.Fa big
95is returned;
96if
97.Fa little
98occurs nowhere in
99.Fa big ,
100.Dv NULL
101is returned;
102otherwise a pointer to the first character of the first occurrence of
103.Fa little
104is returned.
105.Sh EXAMPLES
106The following sets the pointer
107.Va ptr
108to the
109.Qq Li Bar Baz
110portion of
111.Va largestring :
112.Bd -literal -offset indent
113const char *largestring = "Foo Bar Baz";
114const char *smallstring = "Bar";
115char *ptr;
116
117ptr = strstr(largestring, smallstring);
118.Ed
119.Pp
120The following sets the pointer
121.Va ptr
122to
123.Dv NULL ,
124because only the first 4 characters of
125.Va largestring
126are searched:
127.Bd -literal -offset indent
128const char *largestring = "Foo Bar Baz";
129const char *smallstring = "Bar";
130char *ptr;
131
132ptr = strnstr(largestring, smallstring, 4);
133.Ed
134.Sh SEE ALSO
135.Xr memchr 3 ,
136.Xr strchr 3 ,
137.Xr strcspn 3 ,
138.Xr strpbrk 3 ,
139.Xr strrchr 3 ,
140.Xr strsep 3 ,
141.Xr strspn 3 ,
142.Xr strtok 3
143.Sh STANDARDS
144The
145.Fn strstr
146function
147conforms to
148.St -isoC .