.\" Copyright (c) 2002-2004 Tim J. Robbins
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.\" $FreeBSD: head/lib/libc/locale/wcrtomb.3 250883 2013-05-21 19:59:37Z ed $
.\"
.Dd May 21, 2013
.Dt WCRTOMB 3
.Os
.Sh NAME
.Nm wcrtomb ,
.Nm c16rtomb ,
.Nm c32rtomb
.Nd "convert a wide-character code to a character (restartable)"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft size_t
.Fn wcrtomb "char * restrict s" "wchar_t c" "mbstate_t * restrict ps"
.In uchar.h
.Ft size_t
.Fn c16rtomb "char * restrict s" "char16_t c" "mbstate_t * restrict ps"
.Ft size_t
.Fn c32rtomb "char * restrict s" "char32_t c" "mbstate_t * restrict ps"
.Sh DESCRIPTION
The
.Fn wcrtomb ,
.Fn c16rtomb
and
.Fn c32rtomb
functions store a multibyte sequence representing the
wide character
.Fa c ,
including any necessary shift sequences, to the
character array
.Fa s ,
storing a maximum of
.Dv MB_CUR_MAX
bytes.
.Pp
If
.Fa s
is
.Dv NULL ,
these functions behave as if
.Fa s
pointed to an internal buffer and
.Fa c
was a null wide character (L'\e0').
.Pp
The
.Ft mbstate_t
argument,
.Fa ps ,
is used to keep track of the shift state.
If it is
.Dv NULL ,
these functions use an internal, static
.Vt mbstate_t
object, which is initialized to the initial conversion state
at program startup.
.Pp
As certain multibyte characters may only be represented by a series of
16-bit characters, the
.Fn c16rtomb
may need to invoked multiple times before a multibyte sequence is
returned.
.Sh RETURN VALUES
These functions return the length (in bytes) of the multibyte sequence
needed to represent
.Fa c ,
or
.Po Vt size_t Pc Ns \-1
if
.Fa c
is not a valid wide character code.
.Sh ERRORS
The
.Fn wcrtomb ,
.Fn c16rtomb
and
.Fn c32rtomb
functions will fail if:
.Bl -tag -width Er
.It Bq Er EILSEQ
An invalid wide character code was specified.
.It Bq Er EINVAL
The conversion state is invalid.
.El
.Sh SEE ALSO
.Xr mbrtowc 3 ,
.Xr multibyte 3 ,
.Xr setlocale 3 ,
.Xr wctomb 3
.Sh STANDARDS
The
.Fn wcrtomb ,
.Fn c16rtomb
and
.Fn c32rtomb
functions conform to
.St -isoC-2011 .