181 lines
4.8 KiB
Groff
181 lines
4.8 KiB
Groff
.\" $NetBSD: mbtowc.3,v 1.6 2004/01/24 16:58:54 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 MBTOWC 3
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.Os
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.\" ----------------------------------------------------------------------
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.Sh NAME
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.Nm mbtowc
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.Nd converts a multibyte character to a wide 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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.In stdlib.h
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.Ft int
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.Fn mbtowc "wchar_t * restrict pwc" "const char * restrict s" "size_t n"
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.Sh DESCRIPTION
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.Fn mbtowc
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usually converts the multibyte character pointed to by
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.Fa s
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to a wide character, and stores it in the wchar_t object pointed to by
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.Fa pwc
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if
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.Fa pwc
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is non-null and
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.Fa s
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points to a valid character.
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This function may inspect at most 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 to the special sequence bytes to change the shift-state.
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Although such sequence bytes correspond to no individual
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wide-character code,
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.Fn mbtowc
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changes its own state by the sequence bytes 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 mbrtowc 3 ,
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the first
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.Fa n
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bytes pointed to 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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Calling any other functions in
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.Lb libc
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never changes the internal state of
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.Fn mbtowc ,
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except for calling
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.Xr setlocale 3
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with changing the
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.Dv LC_CTYPE
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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
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.Fn mbtowc
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is affected by the
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.Dv LC_CTYPE
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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 012345678901
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.It s == NULL
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.Fn mbtowc
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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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In this case,
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.Fa pwc
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is completely ignored.
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.It pwc == NULL
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.Fn mbtowc
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executes the conversion as if
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.Fa pwc
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is non-null, but a result of the conversion is discarded.
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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 to by
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.Fa s
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never form a complete character.
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Thus, the
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.Fn mbtowc
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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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Normally, the
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.Fn mbtowc
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returns:
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.Bl -tag -width 012345678901
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.It 0
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.Fa s
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points to a null byte
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.Pq Sq \e0 .
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.It positive
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Number of bytes for the valid multibyte character pointed to by
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.Fa s .
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There are no cases that the value returned is greater than
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the value of the
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.Dv MB_CUR_MAX
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macro.
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.It -1
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.Fa s
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points to an invalid or an incomplete multibyte character.
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The
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.Fn mbtowc
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also sets
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.Va errno
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to indicate the error.
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.El
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.Pp
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When
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.Fa s
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is equal to
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.Dv NULL ,
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.Fn mbtowc
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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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.Fn mbtowc
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may cause 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 to 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 mblen 3 ,
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.Xr mbrtowc 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 mbtowc
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function conforms to
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.St -ansiC .
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The restrict qualifier is added at
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.St -isoC-99 .
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