.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
.\"
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.TH WCSRTOMBS 3  2011-10-16 "GNU" "Linux Programmer's Manual"
.SH NAME
wcsrtombs \- convert a wide-character string to a multibyte string
.SH SYNOPSIS
.nf
.B #include <wchar.h>
.sp
.BI "size_t wcsrtombs(char *" dest ", const wchar_t **" src ,
.BI "                 size_t " len ", mbstate_t *" ps );
.fi
.SH DESCRIPTION
If \fIdest\fP is not a NULL pointer,
the
.BR wcsrtombs ()
function converts
the wide-character string \fI*src\fP to a multibyte string starting at
\fIdest\fP.
At most \fIlen\fP bytes are written to \fIdest\fP.
The shift state
\fI*ps\fP is updated.
The conversion is effectively performed by repeatedly
calling
.IR "wcrtomb(dest, *src, ps)" ,
as long as this call succeeds,
and then incrementing \fIdest\fP by the
number of bytes written and \fI*src\fP
by one.
The conversion can stop for three reasons:
.PP
1. A wide character has been encountered that can not be represented as a
multibyte sequence (according to the current locale).
In this case \fI*src\fP
is left pointing to the invalid wide character,
.I (size_t)\ \-1
is returned,
and
.I errno
is set to \fBEILSEQ\fP.
.PP
2. The length limit forces a stop.
In this case \fI*src\fP is left pointing
to the next wide character to be converted,
and the number of bytes written to
\fIdest\fP is returned.
.PP
3. The wide-character string has been completely converted, including the
terminating null wide character (L\(aq\\0\(aq),
which has the side effect of bringing back \fI*ps\fP
to the initial state.
In this case \fI*src\fP is set to NULL, and the number
of bytes written to \fIdest\fP,
excluding the terminating null byte (\(aq\\0\(aq),
is returned.
.PP
If \fIdest\fP is NULL, \fIlen\fP is ignored,
and the conversion proceeds as above, except that the converted bytes
are not written out to memory, and that
no length limit exists.
.PP
In both of the above cases,
if \fIps\fP is a NULL pointer, a static anonymous
state only known to the wcsrtombs function is used instead.
.PP
The programmer must ensure that there is room for at least \fIlen\fP bytes
at \fIdest\fP.
.SH "RETURN VALUE"
The
.BR wcsrtombs ()
function returns
the number of bytes that make up the
converted part of multibyte sequence,
not including the terminating null byte.
If a wide character was encountered
which could not be converted,
.I (size_t)\ \-1
is returned, and
.I errno
set to \fBEILSEQ\fP.
.SH "CONFORMING TO"
C99.
.SH NOTES
The behavior of
.BR wcsrtombs ()
depends on the
.B LC_CTYPE
category of the
current locale.
.PP
Passing NULL as \fIps\fP is not multithread safe.
.SH "SEE ALSO"
.BR iconv (3),
.BR wcsnrtombs (3),
.BR wcstombs (3)
.SH COLOPHON
This page is part of release 3.44 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.