Add nsswitch support.
[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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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 $
d0de9052 39.\" $DragonFly: src/lib/libc/string/strstr.3,v 1.5 2005/08/05 22:35:10 swildner Exp $
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40.\"
41.Dd October 11, 2001
42.Dt STRSTR 3
43.Os
44.Sh NAME
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45.Nm strstr ,
46.Nm strcasestr ,
47.Nm strnstr
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48.Nd locate a substring in a string
49.Sh LIBRARY
50.Lb libc
51.Sh SYNOPSIS
52.In string.h
53.Ft char *
54.Fn strstr "const char *big" "const char *little"
55.Ft char *
56.Fn strcasestr "const char *big" "const char *little"
57.Ft char *
58.Fn strnstr "const char *big" "const char *little" "size_t len"
59.Sh DESCRIPTION
60The
61.Fn strstr
62function
63locates the first occurrence of the null-terminated string
64.Fa little
65in the null-terminated string
66.Fa big .
67.Pp
68The
69.Fn strcasestr
70function is similar to
71.Fn strstr ,
72but ignores the case of both strings.
73.Pp
74The
75.Fn strnstr
76function
77locates the first occurrence of the null-terminated string
78.Fa little
79in the string
80.Fa big ,
81where not more than
82.Fa len
83characters are searched.
84Characters that appear after a
85.Ql \e0
86character are not searched.
87Since the
88.Fn strnstr
89function is a
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90.Fx
91/
92.Dx
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93specific API, it should only be used when portability is not a concern.
94.Sh RETURN VALUES
95If
96.Fa little
97is an empty string,
98.Fa big
99is returned;
100if
101.Fa little
102occurs nowhere in
103.Fa big ,
104.Dv NULL
105is returned;
106otherwise a pointer to the first character of the first occurrence of
107.Fa little
108is returned.
109.Sh EXAMPLES
110The following sets the pointer
111.Va ptr
112to the
113.Qq Li Bar Baz
114portion of
115.Va largestring :
116.Bd -literal -offset indent
117const char *largestring = "Foo Bar Baz";
118const char *smallstring = "Bar";
119char *ptr;
120
121ptr = strstr(largestring, smallstring);
122.Ed
123.Pp
124The following sets the pointer
125.Va ptr
126to
127.Dv NULL ,
128because only the first 4 characters of
129.Va largestring
130are searched:
131.Bd -literal -offset indent
132const char *largestring = "Foo Bar Baz";
133const char *smallstring = "Bar";
134char *ptr;
135
136ptr = strnstr(largestring, smallstring, 4);
137.Ed
138.Sh SEE ALSO
139.Xr memchr 3 ,
140.Xr strchr 3 ,
141.Xr strcspn 3 ,
142.Xr strpbrk 3 ,
143.Xr strrchr 3 ,
144.Xr strsep 3 ,
145.Xr strspn 3 ,
146.Xr strtok 3
147.Sh STANDARDS
148The
149.Fn strstr
150function
151conforms to
152.St -isoC .