.\" $OpenBSD: wcsrtombs.3,v 1.4 2012/06/07 19:47:40 matthew Exp $
.\" $NetBSD: wcsrtombs.3,v 1.6 2003/09/08 17:54:32 wiz Exp $
.\"
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.Dd $Mdocdate: June 7 2012 $
.Dt WCSRTOMBS 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm wcsrtombs ,
.Nm wcsnrtombs
.Nd converts a wide-character string to a multibyte character string \
(restartable)
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.Fd #include <wchar.h>
.Ft size_t
.Fn wcsrtombs "const char * restrict dst" "const wchar_t ** restrict src" \
"size_t len" "mbstate_t * restrict ps"
.Ft size_t
.Fn wcsnrtombs "const char * restrict dst" "const wchar_t ** restrict src" \
"size_t nwc" "size_t len" "mbstate_t * restrict ps"
.\" ----------------------------------------------------------------------
.Sh DESCRIPTION
The
.Fn wcsrtombs
function converts the wide-character string indirectly pointed to by
.Fa src
to the corresponding multibyte character string
and stores it to the array pointed to by
.Fa dst .
The conversion stops due to the following reasons:
.Bl -bullet
.It
The conversion reaches a null wide character.
In this case, the null wide character is also converted.
.It
The conversion has already stored
.Fa len
bytes to the array pointed to by
.Fa dst .
.It
The conversion encounters an invalid character.
.El
.Pp
The
.Fn wcsnrtombs
function is equivalent to
.Fn wcsrtombs
except that it additionally stops the conversion after processing
.Fa nwc
wide characters.
.Pp
Each character will be converted as if
.Xr wcrtomb 3
is continuously called, except the internal state of
.Xr wcrtomb 3
will not be affected.
.Pp
After conversion,
if
.Fa dst
is not a null pointer,
the pointer object pointed to by
.Fa src
is a null pointer (if the conversion is stopped due to reaching a null wide character)
or the address just past the last wide character processed.
.Pp
If
.Fa dst
is not a null pointer and the conversion is stopped due to reaching
a null wide character,
the state object pointed to by
.Fa ps
is set to an initial state after the conversion has taken place.
.Pp
The behaviour of the
.Fn wcsrtombs
and
.Fn wcsnrtombs
functions is affected by the
.Dv LC_CTYPE
category of the current locale.
.Pp
There are two special cases:
.Bl -tag -width 012345678901
.It "dst == NULL"
The conversion takes place, but the resulting multibyte string is discarded.
In this case, the pointer object pointed to by
.Fa src
is not modified and
.Fa len
is ignored.
.It "ps == NULL"
The
.Fn wcsrtombs
and
.Fn wcsnrtombs
functions use their own internal state objects to keep the conversion state,
instead of
.Fa ps
as mentioned in this manual page.
.Pp
Calling any other functions in
.Em libc
never change these internal states,
which are initialized at startup time of the program.
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
The
.Fn wcsrtombs
and
.Fn wcsnrtombs
functions return:
.Bl -tag -width 012345678901
.It 0 or positive
Number of bytes stored to the array pointed to by
.Fa dst ,
except for a null byte.
There is no cases that the value returned is greater than
.Fa len
(unless
.Fa dst
is a null pointer).
If the return value is equal to
.Fa len ,
the string pointed to by
.Fa dst
will not be null-terminated.
.It (size_t)-1
.Fa src
points to the string containing invalid wide character.
In this case,
.Va errno
is set to indicate the error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
The
.Fn wcsrtombs
and
.Fn wcsnrtombs
functions may return the following errors:
.Bl -tag -width Er
.It Bq Er EILSEQ
.Fa src
points to the string containing an invalid wide character.
.It Bq Er EINVAL
.Fa ps
points to an invalid or uninitialized mbstate_t object.
.El
.\" ----------------------------------------------------------------------
.Sh SEE ALSO
.Xr setlocale 3 ,
.Xr wcrtomb 3 ,
.Xr wcstombs 3
.\" ----------------------------------------------------------------------
.Sh STANDARDS
The
.Fn wcsrtombs
function conforms to
.St -ansiC .
The restrict qualifier is added at
.\" .St -isoC99 .
ISO/IEC 9899/AMD1:1995
.Pq Dq ISO C99 .
.Pp
The
.Fn wcsnrtombs
function conforms to
.St -p1003.1-2008 .