.\" $OpenBSD: wcsrtombs.3,v 1.2 2007/05/31 19:19:29 jmc Exp $
.\" $NetBSD: wcsrtombs.3,v 1.6 2003/09/08 17:54:32 wiz Exp $
.\"
.\" Copyright (c)2002 Citrus Project,
.\" All rights reserved.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.Dd $Mdocdate: May 31 2007 $
.Dt WCSRTOMBS 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm wcsrtombs
.Nd converts a wide character string to a multibyte character string \
(restartable)
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.Fd #include <stdlib.h>
.Ft size_t
.Fn wcsrtombs "const char * restrict s" "const wchar_t ** restrict pwcs" \
"size_t n" "mbstate_t * restrict ps"
.\" ----------------------------------------------------------------------
.Sh DESCRIPTION
The
.Fn wcsrtombs
converts the null-terminated wide character string indirectly pointed to by
.Fa pwcs
to the corresponding multibyte character string,
and store it to the array pointed to by
.Fa s .
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
.Fn wcsrtombs
has already stored
.Fa n
bytes to the array pointed to by
.Fa s .
.It
The conversion encounters an invalid character.
.El
.Pp
Each characters 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 s
is not a
.Dv NULL
pointer,
the pointer object pointed to by
.Fa pwcs
is a
.Dv NULL
pointer (if the conversion is stopped due to reaching a null wide character)
or the first byte of the character just after the last character converted.
.Pp
If
.Fa s
is not a null pointer and the conversion is stopped due to reaching
a null wide character, the
.Fn wcsrtombs
places the state object pointed to by
.Fa ps
to an initial state after the conversion is taken place.
.Pp
The behaviour of the
.Fn wcsrtombs
is affected by the
.Dv LC_CTYPE
category of the current locale.
.Pp
These are the special cases:
.Bl -tag -width 012345678901
.It "s == NULL"
.Fn wcsrtombs
returns the number of bytes to store the whole multibyte character string
corresponding to the wide character string pointed to by
.Fa pwcs ,
not including the terminating null byte.
In this case,
.Fa n
is ignored.
.It "pwcs == NULL || *pwcs == NULL"
Undefined (may causes the program to crash).
.It "ps == NULL"
.Fn wcsrtombs
uses its own internal state object to keep the conversion state,
instead of
.Fa ps
mentioned in this manual page.
.Pp
Calling any other functions in
.Em libc
never change the internal
state of
.Fn wcsrtombs ,
that is initialized at startup time of the program.
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
.Fn wcsrtombs
returns:
.Bl -tag -width 012345678901
.It 0 or positive
Number of bytes stored to the array pointed to by
.Fa s ,
except for a null byte.
There is no cases that the value returned is greater than
.Fa n
(unless
.Fa s
is a null pointer).
If the return value is equal to
.Fa n ,
the string pointed to by
.Fa s
will not be null-terminated.
.It (size_t)-1
.Fa pwcs
points to the string containing invalid wide character.
The
.Fn wcsrtombs
also sets errno to indicate the error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
.Fn wcsrtombs
may cause an error in the following cases:
.Bl -tag -width Er
.It Bq Er EILSEQ
.Fa pwcs
points to the string containing an invalid wide character.
.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 .