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<title>Loads a PHP extension at runtime</title>
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</div><hr /><div id="function.dl" class="refentry">
<div class="refnamediv">
<h1 class="refname">dl</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">dl</span> — <span class="dc-title">Loads a PHP extension at runtime</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.dl-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>dl</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$library</code></span>
)</div>
<p class="para rdfs-comment">
Loads the PHP extension given by the parameter
<em><code class="parameter">library</code></em>.
</p>
<p class="para">
Use <span class="function"><a href="function.extension-loaded.html" class="function">extension_loaded()</a></span> to test whether a given
extension is already available or not. This works on both built-in
extensions and dynamically loaded ones (either through <var class="filename">php.ini</var> or
<span class="function"><strong>dl()</strong></span>).
</p>
<div class="warning"><strong class="warning">Warning</strong>
<p class="simpara">
This function has been removed from some SAPIs in PHP 5.3.
</p>
</div>
</div>
<div class="refsect1 parameters" id="refsect1-function.dl-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">library</code></em></span>
<dd>
<p class="para">
This parameter is <em class="emphasis">only</em> the filename of the
extension to load which also depends on your platform. For example,
the <a href="ref.sockets.html" class="link">sockets</a> extension (if compiled
as a shared module, not the default!) would be called
<var class="filename">sockets.so</var> on Unix platforms whereas it is called
<var class="filename">php_sockets.dll</var> on the Windows platform.
</p>
<p class="para">
The directory where the extension is loaded from depends on your
platform:
</p>
<p class="para">
Windows - If not explicitly set in the <var class="filename">php.ini</var>, the extension is
loaded from <var class="filename">C:\php4\extensions\</var> (PHP 4) or
<var class="filename">C:\php5\</var> (PHP 5) by default.
</p>
<p class="para">
Unix - If not explicitly set in the <var class="filename">php.ini</var>, the default extension
directory depends on
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
whether PHP has been built with <em>--enable-debug</em>
or not
</span>
</li>
<li class="listitem">
<span class="simpara">
whether PHP has been built with (experimental) ZTS (Zend Thread Safety)
support or not
</span>
</li>
<li class="listitem">
<span class="simpara">
the current internal <em>ZEND_MODULE_API_NO</em> (Zend
internal module API number, which is basically the date on which a
major module API change happened, e.g. <em>20010901</em>)
</span>
</li>
</ul>
Taking into account the above, the directory then defaults to
<em><install-dir>/lib/php/extensions/ <debug-or-not>-<zts-or-not>-ZEND_MODULE_API_NO</em>,
e.g.
<var class="filename">/usr/local/php/lib/php/extensions/debug-non-zts-20010901</var>
or
<var class="filename">/usr/local/php/lib/php/extensions/no-debug-zts-20010901</var>.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.dl-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure. If the functionality of loading modules is not available
or has been disabled (either by setting
<a href="info.configuration.html#ini.enable-dl" class="link">enable_dl</a> off or by enabling <a href="ini.sect.safe-mode.html#ini.safe-mode" class="link">safe mode</a>
in <var class="filename">php.ini</var>) an <strong><code>E_ERROR</code></strong> is emitted
and execution is stopped. If <span class="function"><strong>dl()</strong></span> fails because the
specified library couldn't be loaded, in addition to <strong><code>FALSE</code></strong> an
<strong><code>E_WARNING</code></strong> message is emitted.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.dl-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-482">
<p><strong>Example #1 <span class="function"><strong>dl()</strong></span> examples</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">// Example loading an extension based on OS<br /></span><span style="color: #007700">if (!</span><span style="color: #0000BB">extension_loaded</span><span style="color: #007700">(</span><span style="color: #DD0000">'sqlite'</span><span style="color: #007700">)) {<br /> if (</span><span style="color: #0000BB">strtoupper</span><span style="color: #007700">(</span><span style="color: #0000BB">substr</span><span style="color: #007700">(</span><span style="color: #0000BB">PHP_OS</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">)) === </span><span style="color: #DD0000">'WIN'</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">dl</span><span style="color: #007700">(</span><span style="color: #DD0000">'php_sqlite.dll'</span><span style="color: #007700">);<br /> } else {<br /> </span><span style="color: #0000BB">dl</span><span style="color: #007700">(</span><span style="color: #DD0000">'sqlite.so'</span><span style="color: #007700">);<br /> }<br />}<br /><br /></span><span style="color: #FF8000">// Or, the PHP_SHLIB_SUFFIX constant is available as of PHP 4.3.0<br /></span><span style="color: #007700">if (!</span><span style="color: #0000BB">extension_loaded</span><span style="color: #007700">(</span><span style="color: #DD0000">'sqlite'</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$prefix </span><span style="color: #007700">= (</span><span style="color: #0000BB">PHP_SHLIB_SUFFIX </span><span style="color: #007700">=== </span><span style="color: #DD0000">'dll'</span><span style="color: #007700">) ? </span><span style="color: #DD0000">'php_' </span><span style="color: #007700">: </span><span style="color: #DD0000">''</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">dl</span><span style="color: #007700">(</span><span style="color: #0000BB">$prefix </span><span style="color: #007700">. </span><span style="color: #DD0000">'sqlite.' </span><span style="color: #007700">. </span><span style="color: #0000BB">PHP_SHLIB_SUFFIX</span><span style="color: #007700">);<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.dl-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>5.3.0</td>
<td>
<span class="function"><strong>dl()</strong></span> is now disabled in some SAPIs due to
stability issues. The only SAPIs that
allow <span class="function"><strong>dl()</strong></span> are CLI and Embed. Use
the <a href="ini.core.html#ini.extension" class="link">Extension Loading
Directives</a> instead.
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.dl-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
<span class="function"><strong>dl()</strong></span> is <em class="emphasis">not</em> supported when
PHP is built with ZTS support. Use
the <a href="ini.core.html#ini.extension" class="link">Extension Loading
Directives</a> instead.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
<span class="function"><strong>dl()</strong></span> is case sensitive on Unix platforms.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">This function is disabled when PHP is running in <a href="features.safe-mode.html" class="link">safe mode</a>.</span></p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-function.dl-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"><a href="ini.core.html#ini.extension" class="link">Extension Loading Directives</a></li>
<li class="member"> <span class="function"><a href="function.extension-loaded.html" class="function" rel="rdfs-seeAlso">extension_loaded()</a> - Find out whether an extension is loaded</span></li>
</ul>
</p>
</div>
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