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freebsd/lib/libc/locale/mbrtowc.3

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.\" Copyright (c) 2002 Tim J. Robbins
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" 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
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.\" documentation and/or other materials provided with the distribution.
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR 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)
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.\" $FreeBSD$
.Dd August 15, 2002
.Dt MBRTOWC 3
.Os
.Sh NAME
.Nm mbrtowc
.Nd "convert a character to a wide-character code (restartable)"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft size_t
.Fn mbrtowc "wchar_t * restrict pwc" "const char * restrict s" "size_t n" "mbstate_t * restrict ps"
.Sh DESCRIPTION
The
.Fn mbrtowc
function inspects at most
.Fa n
bytes pointed to by
.Fa s
and interprets them as a multibyte character sequence
according to the current setting of
.Ev LC_CTYPE .
If
.Fa pwc
is not
.Dv NULL ,
the multibyte character which
.Fa s
represents is stored in the
.Ft wchar_t
it points to.
.Pp
If
.Fa s
is
.Dv NULL ,
.Fn mbrtowc
behaves as if
.Fa pwc
was
.Dv NULL ,
.Fa s
was an empty string ("")
and
.Fa n
was 1.
.Pp
The
.Ft mbstate_t
argument,
.Fa ps ,
is used to keep track of the shift state.
If it is
.Dv NULL ,
.Fn mbrtowc
uses an internal, static
.Ft mbstate_t
object.
.Sh RETURN VALUES
The
.Fn mbrtowc
functions returns:
.Bl -tag -width indent
.It 0
The first
.Fa n
or fewer bytes of
.Fa s
represent the null wide character (L'\e0').
.It >0
The first
.Fa n
or fewer bytes of
.Fa s
represent a valid character,
.Fn mbrtowc
returns the length (in bytes) of the multibyte sequence.
.It Xo
.No ( Ns
.Ft size_t Ns
.No ) Ns \&-2
.Xc
The first
.Fa n
bytes of
.Fa s
are an incomplete multibyte sequence.
.It Xo
.No ( Ns
.Ft size_t Ns
.No ) Ns \&-1
.Xc
The byte sequence pointed to by
.Fa s
is an invalid multibyte sequence.
.El
.Sh ERRORS
The
.Fn mbrtowc
function will fail if:
.Bl -tag -width Er
.\".It Bq Er EINVAL
.\"Invalid argument.
.It Bq Er EILSEQ
An invalid multibyte sequence was detected.
.El
.Sh SEE ALSO
.Xr mbtowc 3 ,
.Xr setlocale 3 ,
.Xr wcrtomb 3
.Sh STANDARDS
The
.Fn mbrtowc
function conforms to
.St -isoC-99 .
.Sh BUGS
The current implementation does not support shift states.