.\" Copyright (c) 2002 Tim J. Robbins
.\" All rights reserved.
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.\" $FreeBSD: src/lib/libc/locale/mbsrtowcs.3,v 1.3 2002/11/29 17:35:09 ru Exp $
.Dd August 16, 2002
.Dt MBSRTOWCS 3
.Os
.Sh NAME
.Nm mbsrtowcs
.Nd "convert a character string to a wide-character string (restartable)"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft size_t
.Fo mbsrtowcs
.Fa "wchar_t * restrict dst" "const char ** restrict src" "size_t len"
.Fa "mbstate_t * restrict ps"
.Fc
.Sh DESCRIPTION
The
.Fn mbsrtowcs
function converts a sequence of multibyte characters pointed to indirectly by
.Fa src
into a sequence of corresponding wide characters and stores at most
.Fa len
of them in the
.Vt wchar_t
array pointed to by
.Fa dst ,
until it encounters a terminating null character
.Pq Li '\e0' .
.Pp
If
.Fa dst
is
.Dv NULL ,
no characters are stored.
.Pp
If
.Fa dst
is not
.Dv NULL ,
the pointer pointed to by
.Fa src
is updated to point to the character after the one that conversion stopped at.
If conversion stops because a null character is encountered,
.Fa *src
is set to
.Dv NULL .
.Pp
The
.Vt mbstate_t
argument,
.Fa ps ,
is used to keep track of the shift state.
If it is
.Dv NULL ,
.Fn mbsrtowcs
uses an internal, static
.Vt mbstate_t
object.
.Sh RETURN VALUES
The
.Fn mbsrtowcs
function returns the number of wide characters stored in
the array pointed to by
.Fa dst
if successful, otherwise it returns
.Po Vt size_t Pc Ns \-1 .
.Sh ERRORS
The
.Fn mbsrtowcs
function will fail if:
.Bl -tag -width Er
.It Bq Er EILSEQ
An invalid multibyte character sequence was encountered.
.El
.Sh SEE ALSO
.Xr mbrtowc 3 ,
.Xr mbstowcs 3 ,
.Xr wcsrtombs 3
.Sh STANDARDS
The
.Fn mbsrtowcs
function conforms to
.St -isoC-99 .
.Sh BUGS
The current implementation does not support shift states.