.\" Copyright (c) 2002-2004 Tim J. Robbins
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.\" $FreeBSD: src/lib/libc/locale/wcsrtombs.3,v 1.5 2004/07/21 10:54:57 tjr Exp $
.\"
.Dd July 21, 2004
.Dt WCSRTOMBS 3
.Os
.Sh NAME
.Nm wcsnrtombs ,
.Nm wcsnrtombs_l ,
.Nm wcsrtombs ,
.Nm wcsrtombs_l
.Nd "convert a wide-character string to a character string (restartable)"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft size_t
.Fo wcsnrtombs
.Fa "char *restrict dst"
.Fa "const wchar_t **restrict src"
.Fa "size_t nwc"
.Fa "size_t len"
.Fa "mbstate_t *restrict ps"
.Fc
.Ft size_t
.Fo wcsrtombs
.Fa "char *restrict dst"
.Fa "const wchar_t **restrict src"
.Fa "size_t len"
.Fa "mbstate_t *restrict ps"
.Fc
.In wchar.h
.In xlocale.h
.Ft size_t
.Fo wcsnrtombs_l
.Fa "char *restrict dst"
.Fa "const wchar_t **restrict src"
.Fa "size_t nwc"
.Fa "size_t len"
.Fa "mbstate_t *restrict ps"
.Fa "locale_t loc"
.Fc
.Ft size_t
.Fo wcsrtombs_l
.Fa "char *restrict dst"
.Fa "const wchar_t **restrict src"
.Fa "size_t len"
.Fa "mbstate_t *restrict ps"
.Fa "locale_t loc"
.Fc
.Sh DESCRIPTION
The
.Fn wcsrtombs
function converts a string of wide characters,
indirectly pointed to by
.Fa src ,
to a corresponding multi-byte character string,
stored in the array pointed to by
.Fa dst .
No more than
.Fa len
bytes are written to
.Fa dst .
.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 wcsrtombs
uses an internal, static
.Vt mbstate_t
object, which is initialized to the initial conversion state
at program startup.
.Pp
The
.Fn wcsnrtombs
function behaves identically to
.Fn wcsrtombs ,
except that conversion stops after reading at most
.Fa nwc
characters from the buffer pointed to by
.Fa src .
.Pp
Although the
.Fn wcsrtombs
and
.Fn wcsnrtombs
functions use the current locale, the
.Fn wcsrtombs_l
and
.Fn wcsnrtombs_l
functions may be passed locales directly. See
.Xr xlocale 3
for more information.
.Sh RETURN VALUES
If successful, the
.Fn wcsrtombs
and
.Fn wcsnrtombs
functions return the number of bytes stored in
the array pointed to by
.Fa dst
(not including any terminating null);
otherwise, they return
.Po Vt size_t Pc Ns \-1 .
.Sh ERRORS
The
.Fn wcsrtombs
and
.Fn wcsnrtombs
functions will fail if:
.Bl -tag -width Er
.It Bq Er EILSEQ
An invalid wide character was encountered.
.It Bq Er EINVAL
The conversion state is invalid.
.El
.Sh SEE ALSO
.Xr mbsrtowcs 3 ,
.Xr wcrtomb 3 ,
.Xr wcstombs 3 ,
.Xr xlocale 3
.Sh STANDARDS
The
.Fn wcsrtombs
function conforms to
.St -isoC-99 .
.Pp
The
.Fn wcsnrtombs
function is an extension to the standard.