.\" $NetBSD: src/lib/libc/locale/wcstombs.3,v 1.7 2004/01/24 16:58:54 wiz Exp $
.\" $DragonFly: src/lib/libc/locale/wcstombs.3,v 1.1 2005/03/12 00:18:01 joerg Exp $
.\"
.\" Copyright (c)2002 Citrus Project,
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 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
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" 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)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd February 4, 2002
.Dt WCSTOMBS 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm wcstombs
.Nd converts a wide character string to a multibyte character string
.\" ----------------------------------------------------------------------
.Sh LIBRARY
.Lb libc
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.In stdlib.h
.Ft size_t
.Fn wcstombs "const char * restrict s" "wchar_t * restrict pwcs" "size_t n"
.\" ----------------------------------------------------------------------
.Sh DESCRIPTION
.Fn wcstombs
converts the null-terminated wide character string pointed to by
.Fa pwcs
to the corresponding multibyte character string,
and stores it in the array pointed to by
.Fa s .
This function may modify the first at most
.Fa n
bytes of the array pointed to by
.Fa s .
Each character will be converted as if
.Xr wctomb 3
is continuously called, except the internal state of
.Xr wctomb 3
will not be affected.
.Pp
For state-dependent encoding, the
.Fn wcstombs
implies the result multibyte character string pointed to by
.Fa s
always to begin with an initial state.
.Pp
The behaviour of
.Fn wcstombs
is affected by the
.Dv LC_CTYPE
category of the current locale.
.Pp
These are the special cases:
.Bl -tag -width 012345678901
.It s == NULL
The
.Fn wcstombs
returns the number of bytes to store the whole multibyte character string
corresponding to the wide character string pointed to by
.Fa pwcs .
In this case,
.Fa n
is ignored.
.It pwcs == NULL
Undefined (may cause the program to crash).
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
.Fn wcstombs
returns:
.Bl -tag -width 012345678901
.It 0 or positive
Number of bytes stored in the array pointed to by
.Fa s .
There are no cases that the value returned is greater than
.Fa n
(unless
.Fa s
is a null pointer).
If the return value is equal to
.Fa n ,
the string pointed to by
.Fa s
will not be null-terminated.
.It (size_t)-1
.Fa pwcs
points to a string containing an invalid wide character.
.Fn wcstombs
also sets
.Va errno
to indicate the error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
.Fn wcstombs
may cause an error in the following case:
.Bl -tag -width Er
.It Bq Er EILSEQ
.Fa pwcs
points to a string containing an invalid wide character.
.El
.\" ----------------------------------------------------------------------
.Sh SEE ALSO
.Xr setlocale 3 ,
.Xr wctomb 3
.\" ----------------------------------------------------------------------
.Sh STANDARDS
The
.Fn wcstombs
function conforms to
.St -ansiC .
The restrict qualifier is added at
.St -isoC-99 .