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.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" References consulted:
.\"   GNU glibc-2 source code and manual
.\"   Dinkumware C library reference http://www.dinkumware.com/
.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
.\"
.TH WCSNRTOMBS 3  2011-10-16 "GNU" "Linux Programmer's Manual"
.SH NAME
wcsnrtombs \- convert a wide-character string to a multibyte string
.SH SYNOPSIS
.nf
.B #include <wchar.h>
.sp
.BI "size_t wcsnrtombs(char *" dest ", const wchar_t **" src ", size_t " nwc ,
.BI "                  size_t " len ", mbstate_t *" ps );
.fi
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.BR wcsnrtombs ():
.PD 0
.ad l
.RS 4
.TP 4
Since glibc 2.10:
_XOPEN_SOURCE\ >=\ 700 || _POSIX_C_SOURCE\ >=\ 200809L
.TP
Before glibc 2.10:
_GNU_SOURCE
.RE
.ad
.PD
.SH DESCRIPTION
The
.BR wcsnrtombs ()
function is like the
.BR wcsrtombs (3)
function,
except that the number of wide characters to be converted,
starting at \fI*src\fP, is limited to \fInwc\fP.
.PP
If \fIdest\fP is not a NULL pointer,
the
.BR wcsnrtombs ()
function converts
at most \fInwc\fP wide characters from
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 \fIerrno\fP is set to \fBEILSEQ\fP.
.PP
2. \fInwc\fP wide characters have been
converted without encountering a null wide character (L\(aq\\0\(aq),
or 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 (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 destination 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 wcsnrtombs 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 wcsnrtombs ()
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 \fIerrno\fP set to \fBEILSEQ\fP.
.SH CONFORMING TO
POSIX.1-2008.
.SH NOTES
The behavior of
.BR wcsnrtombs ()
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 wcsrtombs (3)