.\" $NetBSD: wcsrtombs.3,v 1.3 2002/03/25 19:17:02 yamt Exp $
.\"
.\" Copyright (c)2002 Citrus Project,
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.Dd February 4, 2002
.Dt WCSRTOMBS 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm wcsrtombs
.Nd converts a wide character string to a multibyte character string \
(restartable)
.\" ----------------------------------------------------------------------
.Sh LIBRARY
.Lb libc
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.Fd #include \*[Lt]stdlib.h\*[Gt]
.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 by
.Fa pwcs
to the corresponding multibyte character string,
and store it to the array pointed 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 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 NULL pointer,
the pointer object pointed by
.Fa pwcs
is NULL pointer (if the conversion is stopped due to reach a null wide character)
or the first byte of the character just after the last character converted.
.Pp
If
.Fa s
is not null pointer and the conversion is stopped due to reach
a null wide character, the
.Fn wcsrtombs
places the state object pointed by
.Fa ps
to an initial state after the conversion is taken place.
.Pp
The behaviour of the
.Fn wcsrtombs
is affected by LC_CTYPE category of the current locale.
.Pp
There are special cases:
.Bl -tag -width 012345678901
.It "s == NULL"
The
.Fn wcsrtombs
returns the number of bytes to store the whole multibyte character string
corresponding to the wide character string pointed 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"
The
.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 the
.Lb libc
never change the internal
state of the
.Fn wcsrtombs ,
that is initialized at startup time of the program.
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
The
.Fn wcsrtombs
returns:
.Bl -tag -width 012345678901
.It 0 or positive
number of bytes stored to the array pointed 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 by
.Fa s
will not be null-terminated.
.It (size_t)-1
.Fa pwcs
points the string containing invalid wide character.
The
.Fn wcsrtombs
also sets errno to indicate the error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
The
.Fn wcsrtombs
may causes an error in the following case:
.Bl -tag -width Er
.It Bq Er EILSEQ
.Fa pwcs
points the string containing 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 .