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<title>Checks if the class has been defined</title>
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<h1 class="refname">class_exists</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">class_exists</span> — <span class="dc-title">Checks if the class has been defined</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.class-exists-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>class_exists</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$class_name</code></span>
[, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$autoload</code><span class="initializer"> = true</span></span>
] )</div>
<p class="para rdfs-comment">
This function checks whether or not the given class has been defined.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.class-exists-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">class_name</code></em></span>
<dd>
<p class="para">
The class name. The name is matched in a case-insensitive manner.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">autoload</code></em></span>
<dd>
<p class="para">
Whether or not to call <a href="language.oop5.autoload.html" class="link">__autoload</a> by default.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.class-exists-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> if <em><code class="parameter">class_name</code></em> is a defined class,
<strong><code>FALSE</code></strong> otherwise.
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.class-exists-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>5.0.2</td>
<td>
No longer returns <strong><code>TRUE</code></strong> for defined interfaces. Use
<span class="function"><a href="function.interface-exists.html" class="function">interface_exists()</a></span>.
</td>
</tr>
<tr>
<td>5.0.0</td>
<td>
The <em><code class="parameter">autoload</code></em> parameter was added.
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.class-exists-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-5045">
<p><strong>Example #1 <span class="function"><strong>class_exists()</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">// Check that the class exists before trying to use it<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">class_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'MyClass'</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$myclass </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyClass</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
<div class="example" id="example-5046">
<p><strong>Example #2 <em><code class="parameter">autoload</code></em> parameter example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">__autoload</span><span style="color: #007700">(</span><span style="color: #0000BB">$class</span><span style="color: #007700">)<br />{<br /> include(</span><span style="color: #0000BB">$class </span><span style="color: #007700">. </span><span style="color: #DD0000">'.php'</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">// Check to see whether the include declared the class<br /> </span><span style="color: #007700">if (!</span><span style="color: #0000BB">class_exists</span><span style="color: #007700">(</span><span style="color: #0000BB">$class</span><span style="color: #007700">, </span><span style="color: #0000BB">false</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">trigger_error</span><span style="color: #007700">(</span><span style="color: #DD0000">"Unable to load class: </span><span style="color: #0000BB">$class</span><span style="color: #DD0000">"</span><span style="color: #007700">, </span><span style="color: #0000BB">E_USER_WARNING</span><span style="color: #007700">);<br /> }<br />}<br /><br />if (</span><span style="color: #0000BB">class_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'MyClass'</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$myclass </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyClass</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.class-exists-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.function-exists.html" class="function" rel="rdfs-seeAlso">function_exists()</a> - Return TRUE if the given function has been defined</span></li>
<li class="member"> <span class="function"><a href="function.interface-exists.html" class="function" rel="rdfs-seeAlso">interface_exists()</a> - Checks if the interface has been defined</span></li>
<li class="member"> <span class="function"><a href="function.get-declared-classes.html" class="function" rel="rdfs-seeAlso">get_declared_classes()</a> - Returns an array with the name of the defined classes</span></li>
</ul>
</p>
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