.\" Copyright (c) 2002-2004 Tim J. Robbins. All rights reserved.
.\" Copyright (c) 1993
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.\" Donn Seeley of BSDI.
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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
.\"
.Dd April 8, 2004
.Dt MBSTOWCS 3
.Os
.Sh NAME
.Nm mbstowcs
.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 wcstring" "const char * restrict mbstring"
.Fa "size_t nwchars"
.Fc
.Sh DESCRIPTION
The
.Fn mbstowcs
function converts a multibyte character string
.Fa mbstring
beginning in the initial conversion state
into a wide character string
.Fa wcstring .
No more than
.Fa nwchars
wide characters are stored.
A terminating null wide character is appended if there is room.
.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
.Sh STANDARDS
The
.Fn mbstowcs
function conforms to
.St -isoC-99 .