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<title>Checks if the object has this class as one of its parents</title>
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<h1 class="refname">is_subclass_of</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">is_subclass_of</span> — <span class="dc-title">Checks if the object has this class as one of its parents</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.is-subclass-of-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>is_subclass_of</strong></span>
( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$object</code></span>
, <span class="methodparam"><span class="type">string</span> <code class="parameter">$class_name</code></span>
[, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$allow_string</code><span class="initializer"> = <strong><code>TRUE</code></strong></span></span>
] )</div>
<p class="para rdfs-comment">
Checks if the given <em><code class="parameter">object</code></em> has the class
<em><code class="parameter">class_name</code></em> as one of its parents.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.is-subclass-of-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">object</code></em></span>
<dd>
<p class="para">
A class name or an object instance
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">class_name</code></em></span>
<dd>
<p class="para">
The class name
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">allow_string</code></em></span>
<dd>
<p class="para">
If this parameter set to false, string class name as <em><code class="parameter">object</code></em>
is not allowed. This also prevents from calling autoloader if the class doesn't exist.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.is-subclass-of-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
This function returns <strong><code>TRUE</code></strong> if the object <em><code class="parameter">object</code></em>,
belongs to a class which is a subclass of
<em><code class="parameter">class_name</code></em>, <strong><code>FALSE</code></strong> otherwise.
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.is-subclass-of-changelog">
<h3 class="title">Changelog</h3>
<p class="para">
<table class="doctable informaltable">
<thead>
<tr>
<th>Version</th>
<th>Description</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>5.3.9</td>
<td>
Added <em><code class="parameter">allow_string</code></em> parameter
</td>
</tr>
<tr>
<td>5.3.7</td>
<td>
Added support for <em><code class="parameter">class_name</code></em> to work with
interfaces
</td>
</tr>
<tr>
<td>5.0.3</td>
<td>
You may also specify the <em><code class="parameter">object</code></em> parameter as a
string (the name of the class)
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.is-subclass-of-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-5060">
<p><strong>Example #1 <span class="function"><strong>is_subclass_of()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// define a class<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">WidgetFactory<br /></span><span style="color: #007700">{<br /> var </span><span style="color: #0000BB">$oink </span><span style="color: #007700">= </span><span style="color: #DD0000">'moo'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// define a child class<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">WidgetFactory_Child </span><span style="color: #007700">extends </span><span style="color: #0000BB">WidgetFactory<br /></span><span style="color: #007700">{<br /> var </span><span style="color: #0000BB">$oink </span><span style="color: #007700">= </span><span style="color: #DD0000">'oink'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// create a new object<br /></span><span style="color: #0000BB">$WF </span><span style="color: #007700">= new </span><span style="color: #0000BB">WidgetFactory</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">$WFC </span><span style="color: #007700">= new </span><span style="color: #0000BB">WidgetFactory_Child</span><span style="color: #007700">();<br /><br />if (</span><span style="color: #0000BB">is_subclass_of</span><span style="color: #007700">(</span><span style="color: #0000BB">$WFC</span><span style="color: #007700">, </span><span style="color: #DD0000">'WidgetFactory'</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"yes, \$WFC is a subclass of WidgetFactory\n"</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"no, \$WFC is not a subclass of WidgetFactory\n"</span><span style="color: #007700">;<br />}<br /><br /><br />if (</span><span style="color: #0000BB">is_subclass_of</span><span style="color: #007700">(</span><span style="color: #0000BB">$WF</span><span style="color: #007700">, </span><span style="color: #DD0000">'WidgetFactory'</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"yes, \$WF is a subclass of WidgetFactory\n"</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"no, \$WF is not a subclass of WidgetFactory\n"</span><span style="color: #007700">;<br />}<br /><br /><br /></span><span style="color: #FF8000">// usable only since PHP 5.0.3<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">is_subclass_of</span><span style="color: #007700">(</span><span style="color: #DD0000">'WidgetFactory_Child'</span><span style="color: #007700">, </span><span style="color: #DD0000">'WidgetFactory'</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"yes, WidgetFactory_Child is a subclass of WidgetFactory\n"</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"no, WidgetFactory_Child is not a subclass of WidgetFactory\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
yes, $WFC is a subclass of WidgetFactory
no, $WF is not a subclass of WidgetFactory
yes, WidgetFactory_Child is a subclass of WidgetFactory
</pre></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-5061">
<p><strong>Example #2 <span class="function"><strong>is_subclass_of()</strong></span> using interface example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Define the Interface<br /></span><span style="color: #007700">interface </span><span style="color: #0000BB">MyInterface<br /></span><span style="color: #007700">{<br /> public function </span><span style="color: #0000BB">MyFunction</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #FF8000">// Define the class implementation of the interface<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">MyClass </span><span style="color: #007700">implements </span><span style="color: #0000BB">MyInterface<br /></span><span style="color: #007700">{<br /> public function </span><span style="color: #0000BB">MyFunction</span><span style="color: #007700">()<br /> {<br /> return </span><span style="color: #DD0000">"MyClass Implements MyInterface!"</span><span style="color: #007700">;<br /> }<br />}<br /><br /></span><span style="color: #FF8000">// Instantiate the object<br /></span><span style="color: #0000BB">$my_object </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyClass</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">// Works since 5.3.7<br /><br />// Test using the object instance of the class<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">is_subclass_of</span><span style="color: #007700">(</span><span style="color: #0000BB">$my_object</span><span style="color: #007700">, </span><span style="color: #DD0000">'MyInterface'</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"Yes, \$my_object is a subclass of MyInterface\n"</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"No, \$my_object is not a subclass of MyInterface\n"</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// Test using a string of the class name<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">is_subclass_of</span><span style="color: #007700">(</span><span style="color: #DD0000">'MyClass'</span><span style="color: #007700">, </span><span style="color: #DD0000">'MyInterface'</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"Yes, MyClass is a subclass of MyInterface\n"</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"No, MyClass is not a subclass of MyInterface\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
Yes, $my_object is a subclass of MyInterface
Yes, MyClass is a subclass of MyInterface
</pre></div>
</div>
</div>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.is-subclass-of-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">Using this function will use any registered
<a href="language.oop5.autoload.html" class="link">autoloaders</a> if the class is not already known.</p></p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-function.is-subclass-of-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.get-class.html" class="function" rel="rdfs-seeAlso">get_class()</a> - Returns the name of the class of an object</span></li>
<li class="member"> <span class="function"><a href="function.get-parent-class.html" class="function" rel="rdfs-seeAlso">get_parent_class()</a> - Retrieves the parent class name for object or class</span></li>
<li class="member"> <span class="function"><a href="function.is-a.html" class="function" rel="rdfs-seeAlso">is_a()</a> - Checks if the object is of this class or has this class as one of its parents</span></li>
<li class="member"> <span class="function"><a href="function.class-parents.html" class="function" rel="rdfs-seeAlso">class_parents()</a> - Return the parent classes of the given class</span></li>
</ul>
</p>
</div>
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