c4d9468ea0
Avoid using parenthesis enclosure macros (.Pq and .Po/.Pc) with plain text. Not only this slows down the mdoc(7) processing significantly, but it also has an undesired (in this case) effect of disabling hyphenation within the entire enclosed block.
246 lines
6.7 KiB
Groff
246 lines
6.7 KiB
Groff
.\" Copyright (c) 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to Berkeley by
|
|
.\" Donn Seeley of BSDI.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)multibyte.3 8.1 (Berkeley) 6/4/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd June 4, 1993
|
|
.Dt MULTIBYTE 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm mblen ,
|
|
.Nm mbstowcs ,
|
|
.Nm mbtowc ,
|
|
.Nm wcstombs ,
|
|
.Nm wctomb
|
|
.Nd multibyte character support for C
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.Fd #include <stdlib.h>
|
|
.Ft int
|
|
.Fn mblen "const char *mbchar" "size_t nbytes"
|
|
.Ft size_t
|
|
.Fn mbstowcs "wchar_t *wcstring" "const char *mbstring" "size_t nwchars"
|
|
.Ft int
|
|
.Fn mbtowc "wchar_t *wcharp" "const char *mbchar" "size_t nbytes"
|
|
.Ft size_t
|
|
.Fn wcstombs "char *mbstring" "const wchar_t *wcstring" "size_t nbytes"
|
|
.Ft int
|
|
.Fn wctomb "char *mbchar" "wchar_t wchar"
|
|
.Sh DESCRIPTION
|
|
The basic elements of some written natural languages such as Chinese
|
|
cannot be represented uniquely with single C
|
|
.Va char Ns s .
|
|
The C standard supports two different ways of dealing with
|
|
extended natural language encodings,
|
|
.Em wide
|
|
characters and
|
|
.Em multibyte
|
|
characters.
|
|
Wide characters are an internal representation
|
|
which allows each basic element to map
|
|
to a single object of type
|
|
.Va wchar_t .
|
|
Multibyte characters are used for input and output
|
|
and code each basic element as a sequence of C
|
|
.Va char Ns s .
|
|
Individual basic elements may map into one or more
|
|
(up to
|
|
.Dv MB_CHAR_MAX )
|
|
bytes in a multibyte character.
|
|
.Pp
|
|
The current locale
|
|
.Pq Xr setlocale 3
|
|
governs the interpretation of wide and multibyte characters.
|
|
The locale category
|
|
.Dv LC_CTYPE
|
|
specifically controls this interpretation.
|
|
The
|
|
.Va wchar_t
|
|
type is wide enough to hold the largest value
|
|
in the wide character representations for all locales.
|
|
.Pp
|
|
Multibyte strings may contain
|
|
.Sq shift
|
|
indicators to switch to and from
|
|
particular modes within the given representation.
|
|
If explicit bytes are used to signal shifting,
|
|
these are not recognized as separate characters
|
|
but are lumped with a neighboring character.
|
|
There is always a distinguished
|
|
.Sq initial
|
|
shift state.
|
|
The
|
|
.Fn mbstowcs
|
|
and
|
|
.Fn wcstombs
|
|
functions assume that multibyte strings are interpreted
|
|
starting from the initial shift state.
|
|
The
|
|
.Fn mblen ,
|
|
.Fn mbtowc
|
|
and
|
|
.Fn wctomb
|
|
functions maintain static shift state internally.
|
|
A call with a null
|
|
.Fa mbchar
|
|
pointer returns nonzero if the current locale requires shift states,
|
|
zero otherwise;
|
|
if shift states are required, the shift state is reset to the initial state.
|
|
The internal shift states are undefined after a call to
|
|
.Fn setlocale
|
|
with the
|
|
.Dv LC_CTYPE
|
|
or
|
|
.Dv LC_ALL
|
|
categories.
|
|
.Pp
|
|
For convenience in processing,
|
|
the wide character with value 0
|
|
(the null wide character)
|
|
is recognized as the wide character string terminator,
|
|
and the character with value 0
|
|
(the null byte)
|
|
is recognized as the multibyte character string terminator.
|
|
Null bytes are not permitted within multibyte characters.
|
|
.Pp
|
|
The
|
|
.Fn mblen
|
|
function computes the length in bytes
|
|
of a multibyte character
|
|
.Fa mbchar .
|
|
Up to
|
|
.Fa nbytes
|
|
bytes are examined.
|
|
.Pp
|
|
The
|
|
.Fn mbtowc
|
|
function converts a multibyte character
|
|
.Fa mbchar
|
|
into a wide character and stores the result
|
|
in the object pointed to by
|
|
.Fa wcharp .
|
|
Up to
|
|
.Fa nbytes
|
|
bytes are examined.
|
|
.Pp
|
|
The
|
|
.Fn wctomb
|
|
function converts a wide character
|
|
.Fa wchar
|
|
into a multibyte character and stores
|
|
the result in
|
|
.Fa mbchar .
|
|
The object pointed to by
|
|
.Fa mbchar
|
|
must be large enough to accommodate the multibyte character.
|
|
.Pp
|
|
The
|
|
.Fn mbstowcs
|
|
function converts a multibyte character string
|
|
.Fa mbstring
|
|
into a wide character string
|
|
.Fa wcstring .
|
|
No more than
|
|
.Fa nwchars
|
|
wide characters are stored.
|
|
A terminating null wide character is appended if there is room.
|
|
.Pp
|
|
The
|
|
.Fn wcstombs
|
|
function converts a wide character string
|
|
.Fa wcstring
|
|
into a multibyte character string
|
|
.Fa mbstring .
|
|
Up to
|
|
.Fa nbytes
|
|
bytes are stored in
|
|
.Fa mbstring .
|
|
Partial multibyte characters at the end of the string are not stored.
|
|
The multibyte character string is null terminated if there is room.
|
|
.Sh "RETURN VALUES
|
|
If multibyte characters are not supported in the current locale,
|
|
all of these functions will return \-1 if characters can be processed,
|
|
otherwise 0.
|
|
.Pp
|
|
If
|
|
.Fa mbchar
|
|
is
|
|
.Dv NULL ,
|
|
the
|
|
.Fn mblen ,
|
|
.Fn mbtowc
|
|
and
|
|
.Fn wctomb
|
|
functions return nonzero if shift states are supported,
|
|
zero otherwise.
|
|
If
|
|
.Fa mbchar
|
|
is valid,
|
|
then these functions return
|
|
the number of bytes processed in
|
|
.Fa mbchar ,
|
|
or \-1 if no multibyte character
|
|
could be recognized or converted.
|
|
.Pp
|
|
The
|
|
.Fn mbstowcs
|
|
function returns the number of wide characters converted,
|
|
not counting any terminating null wide character.
|
|
The
|
|
.Fn wcstombs
|
|
function returns the number of bytes converted,
|
|
not counting any terminating null byte.
|
|
If any invalid multibyte characters are encountered,
|
|
both functions return \-1.
|
|
.Sh "SEE ALSO
|
|
.Xr mbrune 3 ,
|
|
.Xr rune 3 ,
|
|
.Xr setlocale 3 ,
|
|
.Xr euc 4 ,
|
|
.Xr utf2 4
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn mblen ,
|
|
.Fn mbstowcs ,
|
|
.Fn mbtowc ,
|
|
.Fn wcstombs
|
|
and
|
|
.Fn wctomb
|
|
functions conform to
|
|
.St -isoC .
|
|
.Sh BUGS
|
|
The current implementation does not support shift states.
|