mirror of
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79 lines
1.7 KiB
XML
79 lines
1.7 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<sect1 xml:id="language.types.null">
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<title>NULL</title>
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<para>
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The <type>null</type> type is PHP's unit type, i.e. it has only one value:
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&null;.
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</para>
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<para>
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Undefined, and <function>unset</function> variables will resolve to the
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value &null;.
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</para>
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<sect2 xml:id="language.types.null.syntax">
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<title>Syntax</title>
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<para>
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There is only one value of type <type>null</type>, and that is the
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case-insensitive constant &null;.
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</para>
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<informalexample>
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<programlisting role="php">
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<![CDATA[
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<?php
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$var = NULL;
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?>
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]]>
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</programlisting>
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</informalexample>
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</sect2>
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<sect2 xml:id="language.types.null.casting">
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<title>Casting to &null;</title>
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&warn.deprecated.feature-7-2-0.removed-8-0-0;
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<para>
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Casting a variable to <type>null</type> using <literal>(unset) $var</literal>
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will <emphasis>not</emphasis> remove the variable or unset its value.
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It will only return a &null; value.
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</para>
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</sect2>
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<sect2 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><function>is_null</function></member>
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<member><function>unset</function></member>
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</simplelist>
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</para>
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</sect2>
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</sect1>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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