172 lines
4.8 KiB
Groff
172 lines
4.8 KiB
Groff
.\" $NetBSD: mblen.3,v 1.2 2002/03/18 07:56:28 wiz Exp $
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.\"
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.\" Copyright (c)2002 Citrus Project,
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.\" All rights reserved.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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.Dd February 3, 2002
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.Dt MBLEN 3
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.Os
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.\" ----------------------------------------------------------------------
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.Sh NAME
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.Nm mblen
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.Nd get number of bytes consisting a multibyte character
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.\" ----------------------------------------------------------------------
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.Sh LIBRARY
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.Lb libc
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.\" ----------------------------------------------------------------------
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.Sh SYNOPSIS
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.Fd #include \*[Lt]stdlib.h\*[Gt]
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.Ft int
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.Fn mblen "const char *s" "size_t n"
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.\" ----------------------------------------------------------------------
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.Sh DESCRIPTION
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The
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.Fn mblen
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function usually determines the number of bytes consisting in
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a multibyte character pointed by
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.Fa s
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and return it.
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This function shall only examine max n bytes of the array beginning from
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.Fa s .
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.Pp
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In state-dependent encodings,
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.Fa s
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may point the special sequence bytes to change the shift-state.
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Although such sequence bytes corresponds to no individual
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wide-character code,
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the
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.Fn mblen
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changes the own state by them and treats them
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as if they are a part of the subsequence multibyte character.
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.Pp
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Unlike
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.Xr mbrlen 3 ,
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the first
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.Fa n
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bytes pointed by
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.Fa s
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need to form an entire multibyte character.
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Otherwise, this function causes an error.
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.Pp
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.Fn mblen
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is equivalent to the following call, except the internal state of the
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.Xr mbtowc 3
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function is not affected:
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.Pp
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.Bd -literal
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mbtowc(NULL, s, n);
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.Ed
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.Pp
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Calling any other functions in the
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.Lb libc
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never change the internal
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state of the
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.Fn mblen ,
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except for calling
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.Xr setlocale 3
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with changing LC_CTYPE category of the current locale.
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Such
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.Xr setlocale 3
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call causes the internal state of this function to be indeterminate.
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.Pp
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The behaviour of the
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.Fn mblen
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is affected by LC_CTYPE category of the current locale.
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.Pp
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There are special cases:
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.Bl -tag -width 0123456789
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.It "s == NULL"
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The
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.Fn mblen
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initializes its own internal state to an initial state, and
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determines whether the current encoding is state-dependent.
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This function returns 0 if the encoding is state-independent,
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otherwise non-zero.
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.It "n == 0"
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In this case,
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the first
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.Fa n
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bytes of the array pointed by
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.Fa s
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never form a complete character. Thus, the
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.Fn mblen
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always fails.
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.El
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.\" ----------------------------------------------------------------------
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.Sh RETURN VALUES
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In the usual cases, the
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.Fn mblen
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returns:
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.Bl -tag -width 0123456789
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.It "0"
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.Fa s
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points a null byte (\'\\0\').
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.It "positive"
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The value returned is
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a number of bytes for the valid multibyte character pointed by
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.Fa s .
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There is no cases that this value is greater than
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.Fa n
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or the value of MB_CUR_MAX macro.
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.It "-1"
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.Fa s
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points an invalid or incomplete multibyte character.
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The
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.Fn mblen
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also sets errno to indicate the error.
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.El
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.Pp
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In the case that
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.Fa s
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is equal to NULL, the
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.Fn mblen
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returns:
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.Bl -tag -width 0123456789
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.It "0"
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The current encoding is state-independent.
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.It "non-zero"
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The current encoding is state-dependent.
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.El
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.\" ----------------------------------------------------------------------
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.Sh ERRORS
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The
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.Fn mblen
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may causes an error in the following case:
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.Bl -tag -width Er
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.It Bq Er EILSEQ
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.Fa s
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points an invalid or incomplete multibyte character.
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.El
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.\" ----------------------------------------------------------------------
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.Sh SEE ALSO
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.Xr mbrlen 3 ,
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.Xr mbtowc 3 ,
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.Xr setlocale 3
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.\" ----------------------------------------------------------------------
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.Sh STANDARDS
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The
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.Fn mblen
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function conforms to
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.St -ansiC .
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