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https://github.com/sigmasternchen/php-doc-en
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2da9f129ef
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@133551 c90b9560-bf6c-de11-be94-00142212c4b1
96 lines
2.8 KiB
XML
96 lines
2.8 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.7 $ -->
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<!-- splitted from ./en/functions/var.xml, last change in rev 1.2 -->
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<refentry id="function.empty">
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<refnamediv>
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<refname>empty</refname>
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<refpurpose>Determine whether a variable is empty</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>bool</type><methodname>empty</methodname>
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<methodparam><type>mixed</type><parameter>var</parameter></methodparam>
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</methodsynopsis>
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<para>
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<function>empty</function> returns &false; if
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<parameter>var</parameter> has a non-empty or non-zero value. In
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otherwords, <literal>""</literal>, <literal>0</literal>,
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<literal>"0"</literal>, &null;, &false;, <literal>array()</literal>,
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<literal>var $var;</literal>, and objects with empty properties, are
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all considered empty. &true; is returned if <parameter>var</parameter>
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is empty.
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</para>
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<para>
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<function>empty</function> is the opposite of
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<literal>(boolean) <parameter>var</parameter></literal>,
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except that no warning is generated when the variable is not set.
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See <link linkend="language.types.boolean.casting">converting
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to boolean</link> for more information.
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</para>
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<para>
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<example>
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<title>
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A simple <function>empty</function> / <function>isset</function>
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comparison.
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</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$var = 0;
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// Evaluates to true because $var is empty
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if (empty($var)) {
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echo '$var is either 0, empty, or not set at all';
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}
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// Evaluates as true because $var is set
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if (isset($var)) {
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echo '$var is set even though it is empty';
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}
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?>
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]]>
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</programlisting>
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</example>
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</para>
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¬e.language-construct;
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<note>
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<para>
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<function>empty</function> only checks variables as anything else will
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result in a parse error. In otherwords, the following will not work:
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<command>empty(addslashes($name))</command>.
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</para>
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</note>
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<simpara>
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See also <function>isset</function>,
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<function>unset</function>,
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<function>array_key_exists</function>,
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<function>count</function>,
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<function>strlen</function>, and
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<link linkend="types.comparisons">the type comparison tables</link>.
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</simpara>
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</refsect1>
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</refentry>
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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:"../../../../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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