282 lines
7.8 KiB
HTML
282 lines
7.8 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of ICONV</TITLE>
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</HEAD><BODY>
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<H1>ICONV</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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iconv - perform character set conversion
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/iconv.h">iconv.h</A>></B>
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<B>size_t iconv(iconv_t </B><I>cd</I><B>,</B>
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<B> char **</B><I>inbuf</I><B>, size_t *</B><I>inbytesleft</I><B>,</B>
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<B> char **</B><I>outbuf</I><B>, size_t *</B><I>outbytesleft</I><B>);</B>
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</PRE>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>iconv</B>()
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function converts a sequence of characters in one character encoding
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to a sequence of characters in another character encoding.
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The
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<I>cd</I>
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argument is a conversion descriptor,
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previously created by a call to
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<B><A HREF="/cgi-bin/man/man2html?3+iconv_open">iconv_open</A></B>(3);
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the conversion descriptor defines the character encodings that
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<B>iconv</B>()
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uses for the conversion.
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The
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<I>inbuf</I>
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argument is the address of a variable that points to
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the first character of the input sequence;
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<I>inbytesleft</I>
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indicates the number of bytes in that buffer.
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The
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<I>outbuf</I>
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argument is the address of a variable that points to
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the first byte available in the output buffer;
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<I>outbytesleft</I>
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indicates the number of bytes available in the output buffer.
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<P>
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The main case is when <I>inbuf</I> is not NULL and <I>*inbuf</I> is not NULL.
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In this case, the
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<B>iconv</B>()
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function converts the multibyte sequence
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starting at <I>*inbuf</I> to a multibyte sequence starting at <I>*outbuf</I>.
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At most <I>*inbytesleft</I> bytes, starting at <I>*inbuf</I>, will be read.
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At most <I>*outbytesleft</I> bytes, starting at <I>*outbuf</I>, will be written.
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<P>
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The
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<B>iconv</B>()
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function converts one multibyte character at a time, and for
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each character conversion it increments <I>*inbuf</I> and decrements
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<I>*inbytesleft</I> by the number of converted input bytes, it increments
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<I>*outbuf</I> and decrements <I>*outbytesleft</I> by the number of converted
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output bytes, and it updates the conversion state contained in <I>cd</I>.
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If the character encoding of the input is stateful, the
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<B>iconv</B>()
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function can also convert a sequence of input bytes
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to an update to the conversion state without producing any output bytes;
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such input is called a <I>shift sequence</I>.
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The conversion can stop for four reasons:
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<DL COMPACT>
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<DT id="1">1.<DD>
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An invalid multibyte sequence is encountered in the input.
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In this case,
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it sets <I>errno</I> to <B>EILSEQ</B> and returns
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<I>(size_t) -1</I>.
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<I>*inbuf</I>
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is left pointing to the beginning of the invalid multibyte sequence.
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<DT id="2">2.<DD>
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The input byte sequence has been entirely converted,
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that is, <I>*inbytesleft</I> has gone down to 0.
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In this case,
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<B>iconv</B>()
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returns the number of
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nonreversible conversions performed during this call.
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<DT id="3">3.<DD>
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An incomplete multibyte sequence is encountered in the input, and the
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input byte sequence terminates after it.
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In this case, it sets <I>errno</I> to
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<B>EINVAL</B> and returns
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<I>(size_t) -1</I>.
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<I>*inbuf</I> is left pointing to the
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beginning of the incomplete multibyte sequence.
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<DT id="4">4.<DD>
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The output buffer has no more room for the next converted character.
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In this case, it sets <I>errno</I> to <B>E2BIG</B> and returns
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<I>(size_t) -1</I>.
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</DL>
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<P>
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A different case is when <I>inbuf</I> is NULL or <I>*inbuf</I> is NULL, but
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<I>outbuf</I> is not NULL and <I>*outbuf</I> is not NULL.
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In this case, the
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<B>iconv</B>()
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function attempts to set <I>cd</I>'s conversion state to the
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initial state and store a corresponding shift sequence at <I>*outbuf</I>.
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At most <I>*outbytesleft</I> bytes, starting at <I>*outbuf</I>, will be written.
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If the output buffer has no more room for this reset sequence, it sets
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<I>errno</I> to <B>E2BIG</B> and returns
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<I>(size_t) -1</I>.
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Otherwise, it increments
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<I>*outbuf</I> and decrements <I>*outbytesleft</I> by the number of bytes
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written.
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<P>
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A third case is when <I>inbuf</I> is NULL or <I>*inbuf</I> is NULL, and
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<I>outbuf</I> is NULL or <I>*outbuf</I> is NULL.
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In this case, the
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<B>iconv</B>()
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function sets <I>cd</I>'s conversion state to the initial state.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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The
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<B>iconv</B>()
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function returns the number of characters converted in a
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nonreversible way during this call; reversible conversions are not counted.
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In case of error, it sets <I>errno</I> and returns
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<I>(size_t) -1</I>.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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The following errors can occur, among others:
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<DL COMPACT>
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<DT id="5"><B>E2BIG</B>
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<DD>
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There is not sufficient room at <I>*outbuf</I>.
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<DT id="6"><B>EILSEQ</B>
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<DD>
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An invalid multibyte sequence has been encountered in the input.
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<DT id="7"><B>EINVAL</B>
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<DD>
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An incomplete multibyte sequence has been encountered in the input.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>VERSIONS</H2>
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This function is available in glibc since version 2.1.
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<A NAME="lbAH"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>iconv</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe race:cd<BR></TD></TR>
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</TABLE>
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<P>
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The
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<B>iconv</B>()
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function is MT-Safe, as long as callers arrange for
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mutual exclusion on the
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<I>cd</I>
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argument.
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<A NAME="lbAI"> </A>
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<H2>CONFORMING TO</H2>
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POSIX.1-2001, POSIX.1-2008.
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<A NAME="lbAJ"> </A>
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<H2>NOTES</H2>
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In each series of calls to
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<B>iconv</B>(),
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the last should be one with <I>inbuf</I> or <I>*inbuf</I> equal to NULL,
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in order to flush out any partially converted input.
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<P>
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Although
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<I>inbuf</I>
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and
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<I>outbuf</I>
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are typed as
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<I>char **</I>,
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this does not mean that the objects they point can be interpreted
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as C strings or as arrays of characters:
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the interpretation of character byte sequences is
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handled internally by the conversion functions.
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In some encodings, a zero byte may be a valid part of a multibyte character.
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<P>
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The caller of
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<B>iconv</B>()
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must ensure that the pointers passed to the function are suitable
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for accessing characters in the appropriate character set.
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This includes ensuring correct alignment on platforms that have
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tight restrictions on alignment.
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<A NAME="lbAK"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+iconv_close">iconv_close</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+iconv_open">iconv_open</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?8+iconvconfig">iconvconfig</A></B>(8)
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<A NAME="lbAL"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="8"><A HREF="#lbAB">NAME</A><DD>
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<DT id="9"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="10"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="11"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="12"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="13"><A HREF="#lbAG">VERSIONS</A><DD>
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<DT id="14"><A HREF="#lbAH">ATTRIBUTES</A><DD>
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<DT id="15"><A HREF="#lbAI">CONFORMING TO</A><DD>
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<DT id="16"><A HREF="#lbAJ">NOTES</A><DD>
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<DT id="17"><A HREF="#lbAK">SEE ALSO</A><DD>
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<DT id="18"><A HREF="#lbAL">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:46 GMT, March 31, 2021
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</BODY>
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</HTML>
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