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            <h1>utf8</h1>


  <!--    -->
<ul><li><a href="#NAME">NAME</a><li><a href="#SYNOPSIS">SYNOPSIS</a><li><a href="#DESCRIPTION">DESCRIPTION</a><ul><li><a href="#Utility-functions">Utility functions</a></ul><li><a href="#BUGS">BUGS</a><li><a href="#SEE-ALSO">SEE ALSO</a></ul><a name="NAME"></a><h1>NAME</h1>
<p>utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code</p>
<a name="SYNOPSIS"></a><h1>SYNOPSIS</h1>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">utf8</span><span class="sc">;</span></li><li> <a class="l_k" href="functions/no.html">no</a> <span class="w">utf8</span><span class="sc">;</span></li><li></li><li> <span class="c"># Convert the internal representation of a Perl scalar to/from UTF-8.</span></li><li></li><li> <span class="i">$num_octets</span> = <span class="i">utf8::upgrade</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span><span class="sc">;</span></li><li> <span class="i">$success</span>    = <span class="i">utf8::downgrade</span><span class="s">(</span><span class="i">$string</span>[<span class="cm">,</span> <span class="i">$fail_ok</span>]<span class="s">)</span><span class="sc">;</span></li><li></li><li> <span class="c"># Change each character of a Perl scalar to/from a series of</span></li><li> <span class="c"># characters that represent the UTF-8 bytes of each original character.</span></li><li></li><li> <span class="i">utf8::encode</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span><span class="sc">;</span>  <span class="c"># &quot;\x{100}&quot;  becomes &quot;\xc4\x80&quot;</span></li><li> <span class="i">utf8::decode</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span><span class="sc">;</span>  <span class="c"># &quot;\xc4\x80&quot; becomes &quot;\x{100}&quot;</span></li><li></li><li> <span class="c"># Convert a code point from the platform native character set to</span></li><li> <span class="c"># Unicode, and vice-versa.</span></li><li> <span class="i">$unicode</span> = <span class="i">utf8::native_to_unicode</span><span class="s">(</span><a class="l_k" href="functions/ord.html">ord</a><span class="s">(</span><span class="q">&#39;A&#39;</span><span class="s">)</span><span class="s">)</span><span class="sc">;</span> <span class="c"># returns 65 on both</span></li><li>                                               <span class="c"># ASCII and EBCDIC</span></li><li>                                               <span class="c"># platforms</span></li><li> <span class="i">$native</span> = <span class="i">utf8::unicode_to_native</span><span class="s">(</span><span class="n">65</span><span class="s">)</span><span class="sc">;</span>        <span class="c"># returns 65 on ASCII</span></li><li>                                               <span class="c"># platforms; 193 on</span></li><li>                                               <span class="c"># EBCDIC</span></li><li></li><li> <span class="i">$flag</span> = <span class="i">utf8::is_utf8</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span><span class="sc">;</span> <span class="c"># since Perl 5.8.1</span></li><li> <span class="i">$flag</span> = <span class="i">utf8::valid</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><a name="DESCRIPTION"></a><h1>DESCRIPTION</h1>
<p>The <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">utf8</span></code>
 pragma tells the Perl parser to allow UTF-8 in the
program text in the current lexical scope.  The <code class="inline"><a class="l_k" href="functions/no.html">no</a> <span class="w">utf8</span></code>
 pragma tells Perl
to switch back to treating the source text as literal bytes in the current
lexical scope.  (On EBCDIC platforms, technically it is allowing UTF-EBCDIC,
and not UTF-8, but this distinction is academic, so in this document the term
UTF-8 is used to mean both).</p>
<p><b>Do not use this pragma for anything else than telling Perl that your
script is written in UTF-8.</b> The utility functions described below are
directly usable without <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">utf8</span><span class="sc">;</span></code>
.</p>
<p>Because it is not possible to reliably tell UTF-8 from native 8 bit
encodings, you need either a Byte Order Mark at the beginning of your
source code, or <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">utf8</span><span class="sc">;</span></code>
, to instruct perl.</p>
<p>When UTF-8 becomes the standard source format, this pragma will
effectively become a no-op.</p>
<p>See also the effects of the <code class="inline">-C</code>
 switch and its cousin, the
<code class="inline"><span class="w">PERL_UNICODE</span></code>
 environment variable, in <a href="perlrun.html">perlrun</a>.</p>
<p>Enabling the <code class="inline"><span class="w">utf8</span></code>
 pragma has the following effect:</p>
<ul>
<li>
<p>Bytes in the source text that are not in the ASCII character set will be
treated as being part of a literal UTF-8 sequence.  This includes most
literals such as identifier names, string constants, and constant
regular expression patterns.</p>
</li>
</ul>
<p>Note that if you have non-ASCII, non-UTF-8 bytes in your script (for example
embedded Latin-1 in your string literals), <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">utf8</span></code>
 will be unhappy.  If
you want to have such bytes under <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">utf8</span></code>
, you can disable this pragma
until the end the block (or file, if at top level) by <code class="inline"><a class="l_k" href="functions/no.html">no</a> <span class="w">utf8</span><span class="sc">;</span></code>
.</p>
<a name="Utility-functions"></a><h2>Utility functions</h2>
<p>The following functions are defined in the <code class="inline"><span class="w">utf8::</span></code>
 package by the
Perl core.  You do not need to say <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">utf8</span></code>
 to use these and in fact
you should not say that unless you really want to have UTF-8 source code.</p>
<ul>
<li><a name="*-%24num_octets-%3d-utf8%3a%3aupgrade(%24string)"></a><b><code class="inline"><span class="i">$num_octets</span> = <span class="i">utf8::upgrade</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span></code>
</b>
<p>(Since Perl v5.8.0)
Converts in-place the internal representation of the string from an octet
sequence in the native encoding (Latin-1 or EBCDIC) to UTF-8. The
logical character sequence itself is unchanged.  If <i>$string</i> is already
stored as UTF-8, then this is a no-op. Returns the
number of octets necessary to represent the string as UTF-8.  Can be
used to make sure that the UTF-8 flag is on, so that <code class="inline">\<span class="w">w</span></code>
 or <code class="inline"><a class="l_k" href="functions/lc.html">lc()</a></code>
work as Unicode on strings containing non-ASCII characters whose code points
are below 256.</p>
<p><b>Note that this function does not handle arbitrary encodings</b>;
use <a href="Encode.html">Encode</a> instead.</p>
</li>
<li><a name="*-%24success-%3d-utf8%3a%3adowngrade(%24string%5b%2c-%24fail_ok%5d)"></a><b><code class="inline"><span class="i">$success</span> = <span class="i">utf8::downgrade</span><span class="s">(</span><span class="i">$string</span>[<span class="cm">,</span> <span class="i">$fail_ok</span>]<span class="s">)</span></code>
</b>
<p>(Since Perl v5.8.0)
Converts in-place the internal representation of the string from
UTF-8 to the equivalent octet sequence in the native encoding (Latin-1
or EBCDIC). The logical character sequence itself is unchanged. If
<i>$string</i> is already stored as native 8 bit, then this is a no-op.  Can
be used to
make sure that the UTF-8 flag is off, e.g. when you want to make sure
that the substr() or length() function works with the usually faster
byte algorithm.</p>
<p>Fails if the original UTF-8 sequence cannot be represented in the
native 8 bit encoding. On failure dies or, if the value of <i>$fail_ok</i> is
true, returns false.</p>
<p>Returns true on success.</p>
<p><b>Note that this function does not handle arbitrary encodings</b>;
use <a href="Encode.html">Encode</a> instead.</p>
</li>
<li><a name="*-utf8%3a%3aencode(%24string)"></a><b><code class="inline"><span class="i">utf8::encode</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span></code>
</b>
<p>(Since Perl v5.8.0)
Converts in-place the character sequence to the corresponding octet
sequence in UTF-8. That is, every (possibly wide) character gets
replaced with a sequence of one or more characters that represent the
individual UTF-8 bytes of the character.  The UTF8 flag is turned off.
Returns nothing.</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/my.html">my</a> <span class="i">$a</span> = <span class="q">&quot;\x{100}&quot;</span><span class="sc">;</span> <span class="c"># $a contains one character, with ord 0x100</span></li><li> <span class="i">utf8::encode</span><span class="s">(</span><span class="i">$a</span><span class="s">)</span><span class="sc">;</span>  <span class="c"># $a contains two characters, with ords (on</span></li><li>                    <span class="c"># ASCII platforms) 0xc4 and 0x80.  On EBCDIC</span></li><li>                    <span class="c"># 1047, this would instead be 0x8C and 0x41.</span></li></ol></pre><p><b>Note that this function does not handle arbitrary encodings</b>;
use <a href="Encode.html">Encode</a> instead.</p>
</li>
<li><a name="*-%24success-%3d-utf8%3a%3adecode(%24string)"></a><b><code class="inline"><span class="i">$success</span> = <span class="i">utf8::decode</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span></code>
</b>
<p>(Since Perl v5.8.0)
Attempts to convert in-place the octet sequence encoded as UTF-8 to the
corresponding character sequence. That is, it replaces each sequence of
characters in the string whose ords represent a valid UTF-8 byte
sequence, with the corresponding single character.  The UTF-8 flag is
turned on only if the source string contains multiple-byte UTF-8
characters.  If <i>$string</i> is invalid as UTF-8, returns false;
otherwise returns true.</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/my.html">my</a> <span class="i">$a</span> = <span class="q">&quot;\xc4\x80&quot;</span><span class="sc">;</span> <span class="c"># $a contains two characters, with ords</span></li><li>                     <span class="c"># 0xc4 and 0x80</span></li><li> <span class="i">utf8::decode</span><span class="s">(</span><span class="i">$a</span><span class="s">)</span><span class="sc">;</span>   <span class="c"># On ASCII platforms, $a contains one char,</span></li><li>                     <span class="c"># with ord 0x100.   Since these bytes aren&#39;t</span></li><li>                     <span class="c"># legal UTF-EBCDIC, on EBCDIC platforms, $a is</span></li><li>                     <span class="c"># unchanged and the function returns FALSE.</span></li></ol></pre><p><b>Note that this function does not handle arbitrary encodings</b>;
use <a href="Encode.html">Encode</a> instead.</p>
</li>
<li><a name="*-%24unicode-%3d-utf8%3a%3anative_to_unicode(%24code_point)"></a><b><code class="inline"><span class="i">$unicode</span> = <span class="i">utf8::native_to_unicode</span><span class="s">(</span><span class="i">$code_point</span><span class="s">)</span></code>
</b>
<p>(Since Perl v5.8.0)
This takes an unsigned integer (which represents the ordinal number of a
character (or a code point) on the platform the program is being run on) and
returns its Unicode equivalent value.  Since ASCII platforms natively use the
Unicode code points, this function returns its input on them.  On EBCDIC
platforms it converts from EBCDIC to Unicode.</p>
<p>A meaningless value will currently be returned if the input is not an unsigned
integer.</p>
<p>Since Perl v5.22.0, calls to this function are optimized out on ASCII
platforms, so there is no performance hit in using it there.</p>
</li>
<li><a name="*-%24native-%3d-utf8%3a%3aunicode_to_native(%24code_point)"></a><b><code class="inline"><span class="i">$native</span> = <span class="i">utf8::unicode_to_native</span><span class="s">(</span><span class="i">$code_point</span><span class="s">)</span></code>
</b>
<p>(Since Perl v5.8.0)
This is the inverse of <code class="inline"><span class="i">utf8::native_to_unicode</span><span class="s">(</span><span class="s">)</span></code>
, converting the other
direction.  Again, on ASCII platforms, this returns its input, but on EBCDIC
platforms it will find the native platform code point, given any Unicode one.</p>
<p>A meaningless value will currently be returned if the input is not an unsigned
integer.</p>
<p>Since Perl v5.22.0, calls to this function are optimized out on ASCII
platforms, so there is no performance hit in using it there.</p>
</li>
<li><a name="*-%24flag-%3d-utf8%3a%3ais_utf8(%24string)"></a><b><code class="inline"><span class="i">$flag</span> = <span class="i">utf8::is_utf8</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span></code>
</b>
<p>(Since Perl 5.8.1)  Test whether <i>$string</i> is marked internally as encoded in
UTF-8.  Functionally the same as <code class="inline"><span class="i">Encode::is_utf8</span><span class="s">(</span><span class="s">)</span></code>
.</p>
</li>
<li><a name="*-%24flag-%3d-utf8%3a%3avalid(%24string)"></a><b><code class="inline"><span class="i">$flag</span> = <span class="i">utf8::valid</span><span class="s">(</span><span class="i">$string</span><span class="s">)</span></code>
</b>
<p>[INTERNAL] Test whether <i>$string</i> is in a consistent state regarding
UTF-8.  Will return true if it is well-formed UTF-8 and has the UTF-8 flag
on <b>or</b> if <i>$string</i> is held as bytes (both these states are 'consistent').
Main reason for this routine is to allow Perl's test suite to check
that operations have left strings in a consistent state.  You most
probably want to use <code class="inline"><span class="i">utf8::is_utf8</span><span class="s">(</span><span class="s">)</span></code>
 instead.</p>
</li>
</ul>
<p><code class="inline"><span class="w">utf8::encode</span></code>
 is like <code class="inline"><span class="w">utf8::upgrade</span></code>
, but the UTF8 flag is
cleared.  See <a href="perlunicode.html">perlunicode</a>, and the C API
functions <code class="inline"><a href="perlapi.html#sv_utf8_upgrade">sv_utf8_upgrade</a></code>,
<code class="inline"><a href="perlapi.html#sv_utf8_downgrade">sv_utf8_downgrade in perlapi</a></code>, <code class="inline"><a href="perlapi.html#sv_utf8_encode">sv_utf8_encode in perlapi</a></code>,
and <code class="inline"><a href="perlapi.html#sv_utf8_decode">sv_utf8_decode in perlapi</a></code>, which are wrapped by the Perl functions
<code class="inline"><span class="w">utf8::upgrade</span></code>
, <code class="inline"><span class="w">utf8::downgrade</span></code>
, <code class="inline"><span class="w">utf8::encode</span></code>
 and
<code class="inline"><span class="w">utf8::decode</span></code>
.  Also, the functions <code class="inline"><span class="w">utf8::is_utf8</span></code>
, <code class="inline"><span class="w">utf8::valid</span></code>
,
<code class="inline"><span class="w">utf8::encode</span></code>
, <code class="inline"><span class="w">utf8::decode</span></code>
, <code class="inline"><span class="w">utf8::upgrade</span></code>
, and <code class="inline"><span class="w">utf8::downgrade</span></code>
 are
actually internal, and thus always available, without a <code class="inline"><a class="l_k" href="functions/require.html">require</a> <span class="w">utf8</span></code>

statement.</p>
<a name="BUGS"></a><h1>BUGS</h1>
<p>Some filesystems may not support UTF-8 file names, or they may be supported
incompatibly with Perl.  Therefore UTF-8 names that are visible to the
filesystem, such as module names may not work.</p>
<a name="SEE-ALSO"></a><h1>SEE ALSO</h1>
<p><a href="perlunitut.html">perlunitut</a>, <a href="perluniintro.html">perluniintro</a>, <a href="perlrun.html">perlrun</a>, <a href="bytes.html">bytes</a>, <a href="perlunicode.html">perlunicode</a></p>




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