145 lines
3.8 KiB
Groff
145 lines
3.8 KiB
Groff
.\" Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org>
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.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Chris Torek and the American National Standards Committee X3,
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.\" on Information Processing Systems.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)strstr.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd October 11, 2001
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.Dt STRSTR 3
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.Os
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.Sh NAME
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.Nm strstr , strcasestr , strnstr
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.Nd locate a substring in a string
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In string.h
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.Ft char *
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.Fn strstr "const char *big" "const char *little"
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.Ft char *
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.Fn strcasestr "const char *big" "const char *little"
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.Ft char *
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.Fn strnstr "const char *big" "const char *little" "size_t len"
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.Sh DESCRIPTION
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The
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.Fn strstr
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function
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locates the first occurrence of the null-terminated string
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.Fa little
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in the null-terminated string
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.Fa big .
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.Pp
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The
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.Fn strcasestr
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function is similar to
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.Fn strstr ,
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but ignores the case of both strings.
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.Pp
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The
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.Fn strnstr
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function
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locates the first occurrence of the null-terminated string
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.Fa little
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in the string
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.Fa big ,
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where not more than
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.Fa len
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characters are searched.
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Characters that appear after a
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.Ql \e0
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character are not searched.
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Since the
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.Fn strnstr
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function is a
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.Fx
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specific API, it should only be used when portability is not a concern.
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.Sh RETURN VALUES
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If
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.Fa little
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is an empty string,
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.Fa big
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is returned;
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if
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.Fa little
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occurs nowhere in
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.Fa big ,
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.Dv NULL
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is returned;
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otherwise a pointer to the first character of the first occurrence of
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.Fa little
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is returned.
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.Sh EXAMPLES
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The following sets the pointer
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.Va ptr
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to the
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.Qq Li Bar Baz
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portion of
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.Va largestring :
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.Bd -literal -offset indent
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const char *largestring = "Foo Bar Baz";
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const char *smallstring = "Bar";
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char *ptr;
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ptr = strstr(largestring, smallstring);
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.Ed
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.Pp
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The following sets the pointer
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.Va ptr
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to
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.Dv NULL ,
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because only the first 4 characters of
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.Va largestring
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are searched:
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.Bd -literal -offset indent
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const char *largestring = "Foo Bar Baz";
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const char *smallstring = "Bar";
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char *ptr;
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ptr = strnstr(largestring, smallstring, 4);
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.Ed
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.Sh SEE ALSO
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.Xr memchr 3 ,
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.Xr memmem 3 ,
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.Xr strchr 3 ,
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.Xr strcspn 3 ,
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.Xr strpbrk 3 ,
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.Xr strrchr 3 ,
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.Xr strsep 3 ,
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.Xr strspn 3 ,
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.Xr strtok 3
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.Sh STANDARDS
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The
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.Fn strstr
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function
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conforms to
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.St -isoC .
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