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<title>Searches for an element with a certain id</title>
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<h1 class="refname">DOMDocument::getElementById</h1>
<p class="verinfo">(PHP 5)</p><p class="refpurpose"><span class="refname">DOMDocument::getElementById</span> — <span class="dc-title">Searches for an element with a certain id</span></p>
</div>
<div class="refsect1 description" id="refsect1-domdocument.getelementbyid-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type"><a href="class.domelement.html" class="type DOMElement">DOMElement</a></span> <span class="methodname"><strong>DOMDocument::getElementById</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$elementId</code></span>
)</div>
<p class="para rdfs-comment">
This function is similar to
<a href="domdocument.getelementsbytagname.html" class="xref">DOMDocument::getElementsByTagName</a> but
searches for an element with a given id.
</p>
<p class="para">
For this function to work, you will need either to set some ID attributes
with <a href="domelement.setidattribute.html" class="xref">DOMElement::setIdAttribute</a>
or a DTD which defines an attribute to be of type ID.
In the later case, you will need to validate your document with
<a href="domdocument.validate.html" class="xref">DOMDocument::validate</a>
or <a href="class.domdocument.html#domdocument.props.validateonparse" class="link">DOMDocument::$validateOnParse</a> before using this function.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-domdocument.getelementbyid-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">elementId</code></em></span>
<dd>
<p class="para">
The unique id value for an element.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-domdocument.getelementbyid-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns the <a href="class.domelement.html" class="classname">DOMElement</a> or <strong><code>NULL</code></strong> if the element is
not found.
</p>
</div>
<div class="refsect1 examples" id="refsect1-domdocument.getelementbyid-examples">
<h3 class="title">Examples</h3>
<div class="example" id="example-5402">
<p><strong>Example #1 DOMDocument::getElementById() Example</strong></p>
<div class="example-contents"><p>The following examples use <var class="filename">book.xml</var> which contains the following:</p></div>
<div class="example-contents">
<div class="xmlcode"><pre class="xmlcode"><?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE books [
<!ELEMENT books (book+)>
<!ELEMENT book (title, author+, xhtml:blurb?)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT blurb (#PCDATA)>
<!ELEMENT author (#PCDATA)>
<!ATTLIST books xmlns CDATA #IMPLIED>
<!ATTLIST books xmlns:xhtml CDATA #IMPLIED>
<!ATTLIST book id ID #IMPLIED>
<!ATTLIST author email CDATA #IMPLIED>
]>
<?xml-stylesheet type="text/xsl" href="style.xsl"?>
<books xmlns="http://books.php/" xmlns:xhtml="http://www.w3.org/1999/xhtml">
<book id="php-basics">
<title>PHP Basics</title>
<author email="jim.smith@basics.php">Jim Smith</author>
<author email="jane.smith@basics.php">Jane Smith</author>
<xhtml:blurb><![CDATA[
<p><em>PHP Basics</em> provides an introduction to PHP.</p>
]]></xhtml:blurb>
</book>
<book id="php-advanced">
<title>PHP Advanced Programming</title>
<author email="jon.doe@advanced.php">Jon Doe</author>
</book>
</books></pre>
</div></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /><br />$doc </span><span style="color: #007700">= new </span><span style="color: #0000BB">DomDocument</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">// We need to validate our document before refering to the id<br /></span><span style="color: #0000BB">$doc</span><span style="color: #007700">-></span><span style="color: #0000BB">validateOnParse </span><span style="color: #007700">= </span><span style="color: #0000BB">true</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$doc</span><span style="color: #007700">-></span><span style="color: #0000BB">Load</span><span style="color: #007700">(</span><span style="color: #DD0000">'book.xml'</span><span style="color: #007700">);<br /><br />echo </span><span style="color: #DD0000">"The element whose id is 'php-basics' is: " </span><span style="color: #007700">. </span><span style="color: #0000BB">$doc</span><span style="color: #007700">-></span><span style="color: #0000BB">getElementById</span><span style="color: #007700">(</span><span style="color: #DD0000">'php-basics'</span><span style="color: #007700">)-></span><span style="color: #0000BB">tagName </span><span style="color: #007700">. </span><span style="color: #DD0000">"\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>
The element whose id is 'php-basics' is: book
</pre></div>
</div>
</div>
</div>
<div class="refsect1 seealso" id="refsect1-domdocument.getelementbyid-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="methodname"><a href="domdocument.getelementsbytagname.html" class="methodname" rel="rdfs-seeAlso">DOMDocument::getElementsByTagName()</a> - Searches for all elements with given local tag name</span></li>
</ul>
</p>
</div>
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