.\" Copyright (c) 2002-2004 Tim J. Robbins. All rights reserved.
.\" Copyright (c) 1993
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.\" From @(#)multibyte.3	8.1 (Berkeley) 6/4/93
.\" From FreeBSD: src/lib/libc/locale/multibyte.3,v 1.22 2003/11/08 03:23:11 tjr Exp
.\" $FreeBSD$
.\"
.Dd April 11, 2004
.Dt MBTOWC 3
.Os
.Sh NAME
.Nm mbtowc
.Nd convert a character to a wide-character code
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fo mbtowc
.Fa "wchar_t * restrict wcharp" "const char * restrict mbchar"
.Fa "size_t nbytes"
.Fc
.Sh DESCRIPTION
The
.Fn mbtowc
function converts a multibyte character
.Fa mbchar
into a wide character according to the current conversion state,
and stores the result
in the object pointed to by
.Fa wcharp .
Up to
.Fa nbytes
bytes are examined.
.Pp
A call with a null
.Fa mbchar
pointer returns nonzero if the current encoding requires shift states,
zero otherwise;
if shift states are required, the shift state is reset to the initial state.
.Sh RETURN VALUES
If
.Fa mbchar
is
.Dv NULL ,
the
.Fn mbtowc
function returns nonzero if shift states are supported,
zero otherwise.
.Pp
Otherwise, if
.Fa mbchar
is not a null pointer,
.Fn mbtowc
either returns 0 if
.Fa mbchar
represents the null wide character, or returns
the number of bytes processed in
.Fa mbchar ,
or returns \-1 if no multibyte character
could be recognized or converted.
In this case,
.Fn mbtowc Ns 's
internal conversion state is undefined.
.Sh ERRORS
The
.Fn mbtowc
function will fail if:
.Bl -tag -width Er
.It Bq Er EILSEQ
An invalid multibyte sequence was detected.
.It Bq Er EINVAL
The internal conversion state is invalid.
.El
.Sh SEE ALSO
.Xr btowc 3 ,
.Xr mblen 3 ,
.Xr mbrtowc 3 ,
.Xr mbstowcs 3 ,
.Xr multibyte 3 ,
.Xr wctomb 3
.Sh STANDARDS
The
.Fn mbtowc
function conforms to
.St -isoC-99 .