.\" $OpenBSD: wcrtomb.3,v 1.4 2010/03/26 19:30:41 jmc Exp $
.\" $NetBSD: wcrtomb.3,v 1.4 2003/09/08 17:54:31 wiz Exp $
.\"
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.Dd $Mdocdate: March 26 2010 $
.Dt WCRTOMB 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm wcrtomb
.Nd converts a wide character to a multibyte character (restartable)
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.Fd #include <wchar.h>
.Ft size_t
.Fn wcrtomb "const char * restrict s" "wchar_t wc" "mbstate_t * restrict ps"
.\" ----------------------------------------------------------------------
.Sh DESCRIPTION
.Fn wcrtomb
converts the wide character given by
.Fa wc
to the corresponding multibyte character, and stores it in the array
pointed to by
.Fa s
unless
.Fa s
is a null pointer.
This function will modify the first at most
.Dv MB_CUR_MAX
bytes of the array pointed by
.Fa s .
.Pp
The behaviour of
.Fn wcrtomb
is affected by the
.Dv LC_CTYPE
category of the current locale.
.Pp
These are the special cases:
.Bl -tag -width 012345678901
.It "wc == 0"
For state-dependent encodings,
.Fn wcrtomb
stores a null byte preceded by a special byte sequence (if any)
to return to an initial state to the array pointed by
.Fa s ,
and the state object pointed by
.Fa ps
also returned to an initial state.
.It "s == NULL"
.Fn wcrtomb
just places
.Fa ps
into an initial state.
It is equivalent to the following call:
.Bd -literal -offset indent
wcrtomb(buf, L'\e0', ps);
.Ed
.Pp
Here,
.Fa buf
is a dummy buffer.
In this case,
.Fa wc
is ignored.
.It "ps == NULL"
.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
.Em libc
never change the internal
state of
.Fn mbrtowc ,
which is initialized at startup time of the program.
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
.Fn wcrtomb
returns:
.Bl -tag -width 012345678901
.It "positive"
The number of bytes (including any shift sequences)
which are stored in the array.
.It "(size_t)-1"
.Fa wc
is not a valid wide character.
In this case,
.Fn wcrtomb
also sets
.Va errno
to indicate error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
.Fn wcrtomb
may cause an error in the following cases:
.Bl -tag -width Er
.It Bq Er EILSEQ
.Fa wc
is not a valid wide character.
.It Bq Er EINVAL
.Fa ps
points to 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 .
ISO/IEC 9899/AMD1:1995
.Pq Dq ISO C90, Amendment 1 .
The restrict qualifier is added at
.\" .St -isoC99 .
ISO/IEC 9899/1999
.Pq Dq ISO C99 .