.\" 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: src/lib/libc/locale/mbstowcs.3,v 1.5 2007/01/09 00:28:00 imp Exp $
.\"
.Dd April 8, 2004
.Dt MBSTOWCS 3
.Os
.Sh NAME
.Nm mbstowcs ,
.Nm mbstowcs_l
.Nd convert a character string to a wide-character string
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft size_t
.Fo mbstowcs
.Fa "wchar_t *restrict pwcs"
.Fa "const char *restrict s"
.Fa "size_t n"
.Fc
.In stdlib.h
.In xlocale.h
.Ft size_t
.Fo mbstowcs_l
.Fa "wchar_t *restrict pwcs"
.Fa "const char *restrict s"
.Fa "size_t n"
.Fa "locale_t loc"
.Fc
.Sh DESCRIPTION
The
.Fn mbstowcs
function converts a multibyte character string
.Fa s ,
beginning in the initial conversion state,
into a wide character string
.Fa pwcs .
No more than
.Fa n
wide characters are stored.
A terminating null wide character is appended, if there is room.
.Pp
Although the
.Fn mbstowcs
function uses the current locale, the
.Fn mbstowcs_l
function may be passed a locale directly. See
.Xr xlocale 3
for more information.
.Sh RETURN VALUES
The
.Fn mbstowcs
function returns the number of wide characters converted,
not counting any terminating null wide character, or \-1
if an invalid multibyte character was encountered.
.Sh ERRORS
The
.Fn mbstowcs
function will fail if:
.Bl -tag -width Er
.It Bq Er EILSEQ
An invalid multibyte sequence was detected.
.It Bq Er EINVAL
The conversion state is invalid.
.El
.Sh SEE ALSO
.Xr mbsrtowcs 3 ,
.Xr mbtowc 3 ,
.Xr multibyte 3 ,
.Xr xlocale 3
.Sh STANDARDS
The
.Fn mbstowcs
function conforms to
.St -isoC-99 .