php-doc-en/reference/classobj/functions/property-exists.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.property-exists" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>property_exists</refname>
  <refpurpose>
   Checks if the object or class has a property
  </refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>property_exists</methodname>
   <methodparam><type>mixed</type><parameter>class</parameter></methodparam>
   <methodparam><type>string</type><parameter>property</parameter></methodparam>
  </methodsynopsis>
  <para>
   This function checks if the given <parameter>property</parameter> exists in
   the specified class.
  </para>
  <note>
   <para>
    As opposed with <function>isset</function>,
    <function>property_exists</function> returns &true; even if the property
    has the value &null;.
   </para>
  </note>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>class</parameter></term>
      <listitem>
       <para>
        The class name or an object of the class to test for
       </para>
      </listitem>
     </varlistentry>
    <varlistentry>
     <term><parameter>property</parameter></term>
      <listitem>
       <para>
        The name of the property
       </para>
      </listitem>
     </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns &true; if the property exists, &false; if it doesn't exist or
   &null; in case of an error.
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  &note.uses-autoload;
  <note>
   <para>
    The <function>property_exists</function> function cannot detect properties
    that are magically accessible using the <link
    linkend="language.oop5.overloading.members"><literal>__get</literal></link>
    magic method.
   </para>
  </note>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>5.3.0</entry>
       <entry>
        This function checks the existence of a property independent of 
        accessibility.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>A <function>property_exists</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php

class myClass {
    public $mine;
    private $xpto;
    static protected $test;

    static function test() {
        var_dump(property_exists('myClass', 'xpto')); //true
    }
}

var_dump(property_exists('myClass', 'mine'));   //true
var_dump(property_exists(new myClass, 'mine')); //true
var_dump(property_exists('myClass', 'xpto'));   //true, as of PHP 5.3.0
var_dump(property_exists('myClass', 'bar'));    //false
var_dump(property_exists('myClass', 'test'));   //true, as of PHP 5.3.0
myClass::test();

?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>method_exists</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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