146 lines
3.4 KiB
Groff
146 lines
3.4 KiB
Groff
.\" Copyright (c) 2002 Tim J. Robbins
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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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.\" $FreeBSD$
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.\"
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.Dd November 11, 2002
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.Dt MBRLEN 3
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.Os
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.Sh NAME
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.Nm mbrlen
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.Nd "get number of bytes in a character (restartable)"
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In wchar.h
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.Ft size_t
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.Fn mbrlen "const char * restrict s" "size_t n" "mbstate_t * restrict ps"
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.Sh DESCRIPTION
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The
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.Fn mbrlen
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function determines the number of bytes constituting the
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multibyte character sequence pointed to by
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.Fa s ,
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examining at most
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.Fa n
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bytes.
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.Pp
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The
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.Vt mbstate_t
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argument,
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.Fa ps ,
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is used to keep track of the shift state.
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If it is
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.Dv NULL ,
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.Fn mbrlen
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uses an internal, static
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.Vt mbstate_t
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object.
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.Pp
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It is equivalent to:
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.Pp
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.Dl "mbrtowc(NULL, s, n, ps);"
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.Pp
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Except that when
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.Fa ps
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is a
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.Dv NULL
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pointer,
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.Fn mbrlen
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uses its own static, internal
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.Vt mbstate_t
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object to keep track of the shift state.
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.Sh RETURN VALUES
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The
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.Fn mbrlen
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functions returns:
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.Bl -tag -width indent
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.It 0
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The first
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.Fa n
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or fewer bytes of
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.Fa s
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represent the null wide character
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.Pq Li "L'\e0'" .
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.It >0
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The first
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.Fa n
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or fewer bytes of
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.Fa s
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represent a valid character,
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.Fn mbrtowc
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returns the length (in bytes) of the multibyte sequence.
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.It Po Vt size_t Pc Ns \-2
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The first
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.Fa n
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bytes of
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.Fa s
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are an incomplete multibyte sequence.
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.It Po Vt size_t Pc Ns \-1
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The byte sequence pointed to by
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.Fa s
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is an invalid multibyte sequence.
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.El
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.Sh EXAMPLES
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A function which calculates the number of characters in a multibyte
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character string:
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.Bd -literal -offset indent
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size_t
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nchars(const char *s)
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{
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size_t charlen, chars;
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mbstate_t mbs;
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chars = 0;
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memset(&mbs, 0, sizeof(mbs));
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while ((charlen = mbrlen(s, MB_CUR_MAX, &mbs)) != 0 &&
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charlen != (size_t)-1 && charlen != (size_t)-2) {
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s += charlen;
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chars++;
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}
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return (chars);
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}
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.Ed
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.Sh ERRORS
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The
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.Fn mbrlen
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function will fail if:
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.Bl -tag -width Er
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.\".It Bq Er EINVAL
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.\"Invalid argument.
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.It Bq Er EILSEQ
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An invalid multibyte sequence was detected.
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.El
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.Sh SEE ALSO
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.Xr mblen 3 ,
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.Xr mbrtowc 3
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.Sh STANDARDS
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The
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.Fn mbrlen
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function conforms to
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.St -isoC-99 .
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.Sh BUGS
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The current implementation does not support shift states.
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