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<H1>MBSNRTOWCS</H1>
Section: Linux Programmer's Manual (3)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
mbsnrtowcs - convert a multibyte string to a wide-character string
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<PRE>
<B>#include &lt;<A HREF="file:///usr/include/wchar.h">wchar.h</A>&gt;</B>
<B>size_t mbsnrtowcs(wchar_t *</B><I>dest</I><B>, const char **</B><I>src</I><B>,</B>
<B> size_t </B><I>nms</I><B>, size_t </B><I>len</I><B>, mbstate_t *</B><I>ps</I><B>);</B>
</PRE>
<P>
Feature Test Macro Requirements for glibc (see
<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
<P>
<B>mbsnrtowcs</B>():
<DL COMPACT><DT id="1"><DD>
<DL COMPACT>
<DT id="2">Since glibc 2.10:<DD>
_POSIX_C_SOURCE&nbsp;&gt;=&nbsp;200809L
<DT id="3">Before glibc 2.10:<DD>
_GNU_SOURCE
</DL>
</DL>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
The
<B>mbsnrtowcs</B>()
function is like the
<B><A HREF="/cgi-bin/man/man2html?3+mbsrtowcs">mbsrtowcs</A></B>(3)
function, except that
the number of bytes to be converted, starting at
<I>*src</I>,
is limited to at most
<I>nms</I>
bytes.
<P>
If
<I>dest</I>
is not NULL, the
<B>mbsnrtowcs</B>()
function converts at
most
<I>nms</I>
bytes from the
multibyte string
<I>*src</I>
to a wide-character string starting at
<I>dest</I>.
At most
<I>len</I>
wide characters are written to
<I>dest</I>.
The shift state
<I>*ps</I>
is updated.
The conversion is effectively performed by repeatedly
calling
<I>mbrtowc(dest, *src, n, ps)</I>
where
<I>n</I>
is some
positive number, as long as this call succeeds, and then incrementing
<I>dest</I>
by one and
<I>*src</I>
by the number of bytes consumed.
The
conversion can stop for three reasons:
<DL COMPACT>
<DT id="4">1.<DD>
An invalid multibyte sequence has been encountered.
In this case,
<I>*src</I>
is left pointing to the invalid multibyte sequence,
<I>(size_t)&nbsp;-1</I>
is returned,
and
<I>errno</I>
is set to
<B>EILSEQ</B>.
<DT id="5">2.<DD>
The
<I>nms</I>
limit forces a stop,
or
<I>len</I>
non-L'\0' wide characters
have been stored at
<I>dest</I>.
In this case,
<I>*src</I>
is left pointing to the
next multibyte sequence to be converted, and the number of wide characters
written to
<I>dest</I>
is returned.
<DT id="6">3.<DD>
The multibyte string has been completely converted, including the
terminating null wide character ('\0')
(which has the side effect of bringing back
<I>*ps</I>
to the
initial state).
In this case,
<I>*src</I>
is set to NULL, and the number of wide
characters written to
<I>dest</I>,
excluding the terminating null wide character,
is returned.
</DL>
<P>
According to POSIX.1,
if the input buffer ends with an incomplete character,
it is unspecified whether conversion stops at the end of
the previous character (if any), or at the end of the input buffer.
The glibc implementation adopts the former behavior.
<P>
If
<I>dest</I>
is NULL,
<I>len</I>
is ignored, and the conversion proceeds as
above, except that the converted wide characters
are not written out to memory,
and that no destination length limit exists.
<P>
In both of the above cases, if
<I>ps</I>
is NULL, a static anonymous
state known only to the
<B>mbsnrtowcs</B>()
function is used instead.
<P>
The programmer must ensure that there is room for at least
<I>len</I>
wide
characters at
<I>dest</I>.
<A NAME="lbAE">&nbsp;</A>
<H2>RETURN VALUE</H2>
The
<B>mbsnrtowcs</B>()
function returns the number of wide characters
that make up the converted part of the wide-character string,
not including the terminating null wide character.
If an invalid multibyte sequence was
encountered,
<I>(size_t)&nbsp;-1</I>
is returned, and
<I>errno</I>
set to
<B>EILSEQ</B>.
<A NAME="lbAF">&nbsp;</A>
<H2>ATTRIBUTES</H2>
For an explanation of the terms used in this section, see
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
<TABLE BORDER>
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
<TR VALIGN=top><TD>
<B>mbsnrtowcs</B>()
</TD><TD>Thread safety</TD><TD>MT-Unsafe race:mbsnrtowcs/!ps<BR></TD></TR>
</TABLE>
<P>
<A NAME="lbAG">&nbsp;</A>
<H2>CONFORMING TO</H2>
POSIX.1-2008.
<A NAME="lbAH">&nbsp;</A>
<H2>NOTES</H2>
The behavior of
<B>mbsnrtowcs</B>()
depends on the
<B>LC_CTYPE</B>
category of the
current locale.
<P>
Passing NULL as
<I>ps</I>
is not multithread safe.
<A NAME="lbAI">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?3+iconv">iconv</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+mbrtowc">mbrtowc</A></B>(3)
<B><A HREF="/cgi-bin/man/man2html?3+mbsinit">mbsinit</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+mbsrtowcs">mbsrtowcs</A></B>(3)
<A NAME="lbAJ">&nbsp;</A>
<H2>COLOPHON</H2>
This page is part of release 5.05 of the Linux
<I>man-pages</I>
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="7"><A HREF="#lbAB">NAME</A><DD>
<DT id="8"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="9"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="10"><A HREF="#lbAE">RETURN VALUE</A><DD>
<DT id="11"><A HREF="#lbAF">ATTRIBUTES</A><DD>
<DT id="12"><A HREF="#lbAG">CONFORMING TO</A><DD>
<DT id="13"><A HREF="#lbAH">NOTES</A><DD>
<DT id="14"><A HREF="#lbAI">SEE ALSO</A><DD>
<DT id="15"><A HREF="#lbAJ">COLOPHON</A><DD>
</DL>
<HR>
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