mirror of
https://github.com/sigmasternchen/php-doc-en
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0c9c2dd669
Cf. <https://github.com/php/doc-en/pull/289>. git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@352191 c90b9560-bf6c-de11-be94-00142212c4b1
295 lines
6.8 KiB
XML
295 lines
6.8 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<!-- splitted from ./en/functions/var.xml, last change in rev 1.6 -->
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<refentry xml:id="function.var-export" xmlns="http://docbook.org/ns/docbook">
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<refnamediv>
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<refname>var_export</refname>
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<refpurpose>Outputs or returns a parsable string representation of a variable</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type class="union"><type>string</type><type>null</type></type><methodname>var_export</methodname>
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<methodparam><type>mixed</type><parameter>value</parameter></methodparam>
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<methodparam choice="opt"><type>bool</type><parameter>return</parameter><initializer>&false;</initializer></methodparam>
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</methodsynopsis>
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<simpara>
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<function>var_export</function> gets structured information about the
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given variable. It is similar to <function>var_dump</function>
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with one exception: the returned representation is valid PHP code.
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</simpara>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term><parameter>value</parameter></term>
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<listitem>
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<para>
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The variable you want to export.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>return</parameter></term>
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<listitem>
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<para>
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If used and set to &true;, <function>var_export</function> will return
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the variable representation instead of outputting it.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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Returns the variable representation when the <parameter>return</parameter>
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parameter is used and evaluates to &true;. Otherwise, this function will
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return &null;.
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</para>
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</refsect1>
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<refsect1 role="notes">
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&reftitle.notes;
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¬e.uses-ob;
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</refsect1>
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<refsect1 role="changelog">
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&reftitle.changelog;
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<para>
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<informaltable>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>&Version;</entry>
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<entry>&Description;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>7.3.0</entry>
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<entry>
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Now exports <classname>stdClass</classname> objects as an array cast to
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an object (<code>(object) array( ... )</code>), rather than using the
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nonexistent method <methodname>stdClass::__setState</methodname>.
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The practical effect is that now <classname>stdClass</classname> is
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exportable, and the resulting code will even work on earlier versions of
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PHP.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example>
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<title><function>var_export</function> Examples</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$a = array (1, 2, array ("a", "b", "c"));
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var_export($a);
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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array (
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0 => 1,
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1 => 2,
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2 =>
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array (
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0 => 'a',
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1 => 'b',
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2 => 'c',
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),
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)
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]]>
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</screen>
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<programlisting role="php">
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<![CDATA[
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<?php
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$b = 3.1;
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$v = var_export($b, true);
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echo $v;
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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3.1
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]]>
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</screen>
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</example>
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</para>
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<para>
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<example>
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<title>Exporting stdClass (since PHP 7.3.0)</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$person = new stdClass;
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$person->name = 'ElePHPant ElePHPantsdotter';
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$person->website = 'https://php.net/elephpant.php';
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var_export($person);
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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(object) array(
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'name' => 'ElePHPant ElePHPantsdotter',
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'website' => 'https://php.net/elephpant.php',
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)
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]]>
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</screen>
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</example>
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</para>
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<para>
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<example>
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<title>Exporting classes (since PHP 5.1.0)</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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class A { public $var; }
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$a = new A;
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$a->var = 5;
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var_export($a);
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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A::__set_state(array(
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'var' => 5,
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))
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]]>
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</screen>
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</example>
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</para>
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<para>
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<example>
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<title>Using <link linkend="object.set-state">__set_state()</link> (since PHP 5.1.0)</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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class A
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{
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public $var1;
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public $var2;
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public static function __set_state($an_array)
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{
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$obj = new A;
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$obj->var1 = $an_array['var1'];
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$obj->var2 = $an_array['var2'];
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return $obj;
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}
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}
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$a = new A;
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$a->var1 = 5;
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$a->var2 = 'foo';
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eval('$b = ' . var_export($a, true) . ';'); // $b = A::__set_state(array(
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// 'var1' => 5,
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// 'var2' => 'foo',
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// ));
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var_dump($b);
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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object(A)#2 (2) {
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["var1"]=>
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int(5)
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["var2"]=>
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string(3) "foo"
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}
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]]>
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</screen>
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</example>
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</para>
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</refsect1>
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<refsect1 role="notes">
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&reftitle.notes;
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<note>
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<para>
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Variables of type <type>resource</type> couldn't be exported by this
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function.
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</para>
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</note>
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<note>
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<para>
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<function>var_export</function> does not handle circular references as
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it would be close to impossible to generate parsable PHP code for that.
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If you want to do something with the full representation of an array
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or object, use <function>serialize</function>.
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</para>
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</note>
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<warning>
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<para>
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When <function>var_export</function> exports objects, the leading backslash is not included in the class name of namespaced classes for maximum compatibility.
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</para>
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</warning>
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<note>
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<para>
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To be able to evaluate the PHP generated by <function>var_export</function>,
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all processed objects must implement the magic <link
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linkend="object.set-state">__set_state</link> method. The only exception is
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<classname>stdClass</classname>, which is exported using an array cast to
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an object.
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</para>
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</note>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><function>print_r</function></member>
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<member><function>serialize</function></member>
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<member><function>var_dump</function></member>
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</simplelist>
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</para>
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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:"~/.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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