.\" $NetBSD: wcrtomb.3,v 1.2 2002/03/18 07:56:29 wiz Exp $
.\"
.\" Copyright (c)2002 Citrus Project,
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.Dd February 4, 2002
.Dt WCRTOMB 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm wcrtomb
.Nd converts a wide character to a multibyte character (restartable)
.\" ----------------------------------------------------------------------
.Sh LIBRARY
.Lb libc
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.Fd #include \*[Lt]wchar.h\*[Gt]
.Ft size_t
.Fn wcrtomb "const char * restrict s" "wchar_t wc" "mbstate_t * restrict ps"
.\" ----------------------------------------------------------------------
.Sh DESCRIPTION
The
.Fn wcrtomb
converts the wide character given by
.Fa wc
to the corresponding multibyte character, and stores it to the array
pointed by
.Fa s
unless
.Fa s
is null pointer.
This function will modify the first at most MB_CUR_MAX bytes of the
array pointed by
.Fa s .
.Pp
The behaviour of the
.Fn wcrtomb
is affected by LC_CTYPE category of the current locale.
.Pp
There are the special cases:
.Bl -tag -width 012345678901
.It "wc == 0"
For state-dependent encodings, the
.Fn wcrtomb
stores a null byte preceded by special byte sequence (if any)
to back to a initial state to the array pointed by
.Fa s ,
and the state object pointed by
.Fa ps
also back to a initial state.
.It "s == NULL"
The
.Fn wcrtomb
just places
.Fa ps
into a initial state.
It is equivalent to the following call:
.Bd -literal
wcrtomb(buf, L'\\0', ps);
.Ed
.Pp
Here,
.Fa buf
is a dummy buffer.
In this case,
.Fa wc
is ignored.
.It "ps == NULL"
The
.Fn mbrtowc
uses its own internal state object to keep the conversion state,
instead of
.Fa ps
mentioned in this manual page.
.Pp
Calling any other functions in the
.Lb libc
never change the internal
state of the
.Fn mbrtowc ,
that is initialized at startup time of the program.
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
The
.Fn wcrtomb
returns
.Bl -tag -width 012345678901
.It "positive"
The number of bytes (including any shift sequences)
which is stored in the array.
.It "(size_t)-1"
.Fa wc
is not valid wide character.
In this case, the
.Fn wcrtomb
also sets errno to indicate error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
The
.Fn wcrtomb
may causes an error in the following case:
.Bl -tag -width Er
.It Bq Er EILSEQ
.Fa wc
is not valid wide character.
.It Bq Er EINVAL
.Fa ps
points an invalid or uninitialized mbstate_t object.
.El
.\" ----------------------------------------------------------------------
.Sh SEE ALSO
.Xr setlocale 3 ,
.Xr wctomb 3
.\" ----------------------------------------------------------------------
.Sh STANDARDS
The
.Fn wcrtomb
function conforms to
.St -isoC-amd1 .
The restrict qualifier is added at
.St -isoC99 .