php-doc-en/reference/classobj/functions/is-subclass-of.xml

<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.6 $ -->
<refentry id="function.is-subclass-of">
 <refnamediv>
  <refname>is_subclass_of</refname>
  <refpurpose>Returns &true; if the object has this class as one of its parents</refpurpose>
 </refnamediv>
 <refsect1>
  <title>Description</title>
  <methodsynopsis>
   <type>bool</type><methodname>is_subclass_of</methodname>
   <methodparam><type>mixed</type><parameter>object</parameter></methodparam>
   <methodparam><type>string</type><parameter>class_name</parameter></methodparam>
  </methodsynopsis>
  <para>
   This function returns &true; if the object
   <parameter>object</parameter>, belongs to a class which is a
   subclass of <parameter>class_name</parameter>, &false; otherwise.
  </para>
  <note>
   <para>
    Since PHP 5.0.3 you may also specify the <parameter>object</parameter>
    parameter as a string (the name of the class).
   </para>
  </note>
  <para>
   <example>
    <title><function>is_subclass_of</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
// define a class
class WidgetFactory
{
  var $oink = 'moo';
}

// define a child class
class WidgetFactory_Child extends WidgetFactory
{
  var $oink = 'oink';
}

// create a new object
$WF = new WidgetFactory();
$WFC = new WidgetFactory_Child();

if (is_subclass_of($WFC, 'WidgetFactory')) {
  echo "yes, \$WFC is a subclass of WidgetFactory\n";
} else {
  echo "no, \$WFC is not a subclass of WidgetFactory\n";
}


if (is_subclass_of($WF, 'WidgetFactory')) {
  echo "yes, \$WF is a subclass of WidgetFactory\n";
} else {
  echo "no, \$WF is not a subclass of WidgetFactory\n";
}


// usable only since PHP 5.0.3
if (is_subclass_of('WidgetFactory_Child', 'WidgetFactory')) {
  echo "yes, WidgetFactory_Child is a subclass of WidgetFactory\n";
} else {
  echo "no, WidgetFactory_Child is not a subclass of WidgetFactory\n";
}
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
yes, $WFC is a subclass of WidgetFactory
no, $WF is not a subclass of WidgetFactory
yes, WidgetFactory_Child is a subclass of WidgetFactory
]]>
    </screen>
   </example>
  </para>
  <simpara>
   See also <function>get_class</function>,
   <function>get_parent_class</function> and
   <function>is_a</function>.
  </simpara>
 </refsect1>
</refentry>

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