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<title>The Iterator interface</title>
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</div><hr /><div id="class.iterator" class="reference">
<h1 class="title">The Iterator interface</h1>
<div class="partintro"><p class="verinfo">(PHP 5 >= 5.0.0)</p>
<div class="section" id="iterator.intro">
<h2 class="title">Introduction</h2>
<p class="para">
Interface for external iterators or objects that can be iterated
themselves internally.
</p>
</div>
<div class="section" id="iterator.synopsis">
<h2 class="title">Interface synopsis</h2>
<div class="classsynopsis">
<div class="ooclass"></div>
<div class="classsynopsisinfo">
<span class="ooclass">
<strong class="classname">Iterator</strong>
</span>
<span class="ooclass">
<span class="modifier">extends</span>
<a href="class.traversable.html" class="classname">Traversable</a>
</span>
{</div>
<div class="classsynopsisinfo classsynopsisinfo_comment">/* Methods */</div>
<div class="methodsynopsis dc-description">
<span class="modifier">abstract</span> <span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="iterator.current.html" class="methodname">current</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">abstract</span> <span class="modifier">public</span> <span class="type">scalar</span> <span class="methodname"><a href="iterator.key.html" class="methodname">key</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">abstract</span> <span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="iterator.next.html" class="methodname">next</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">abstract</span> <span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="iterator.rewind.html" class="methodname">rewind</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">abstract</span> <span class="modifier">public</span> <span class="type">boolean</span> <span class="methodname"><a href="iterator.valid.html" class="methodname">valid</a></span>
( <span class="methodparam">void</span>
)</div>
}</div>
</div>
<div class="section" id="iterator.iterators">
<h2 class="title">Predefined iterators</h2>
<p class="para">
PHP already provides a number of iterators for many day to day tasks.
See <a href="spl.iterators.html" class="link">SPL iterators</a> for a list.
</p>
</div>
<div class="section" id="iterator.examples">
<h2 class="title">Examples</h2>
<div class="example" id="iterator.example.basic">
<p><strong>Example #1 Basic usage</strong></p>
<div class="example-contents"><p>
This example demonstrates in which order methods are called when
using <a href="control-structures.foreach.html" class="link">foreach</a> with an iterator.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">myIterator </span><span style="color: #007700">implements </span><span style="color: #0000BB">Iterator </span><span style="color: #007700">{<br /> private </span><span style="color: #0000BB">$position </span><span style="color: #007700">= </span><span style="color: #0000BB">0</span><span style="color: #007700">;<br /> private </span><span style="color: #0000BB">$array </span><span style="color: #007700">= array(<br /> </span><span style="color: #DD0000">"firstelement"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"secondelement"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"lastelement"</span><span style="color: #007700">,<br /> ); <br /><br /> public function </span><span style="color: #0000BB">__construct</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">position </span><span style="color: #007700">= </span><span style="color: #0000BB">0</span><span style="color: #007700">;<br /> }<br /><br /> function </span><span style="color: #0000BB">rewind</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">__METHOD__</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">position </span><span style="color: #007700">= </span><span style="color: #0000BB">0</span><span style="color: #007700">;<br /> }<br /><br /> function </span><span style="color: #0000BB">current</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">__METHOD__</span><span style="color: #007700">);<br /> return </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">array</span><span style="color: #007700">[</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">position</span><span style="color: #007700">];<br /> }<br /><br /> function </span><span style="color: #0000BB">key</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">__METHOD__</span><span style="color: #007700">);<br /> return </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">position</span><span style="color: #007700">;<br /> }<br /><br /> function </span><span style="color: #0000BB">next</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">__METHOD__</span><span style="color: #007700">);<br /> ++</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">position</span><span style="color: #007700">;<br /> }<br /><br /> function </span><span style="color: #0000BB">valid</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">__METHOD__</span><span style="color: #007700">);<br /> return isset(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">array</span><span style="color: #007700">[</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">position</span><span style="color: #007700">]);<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$it </span><span style="color: #007700">= new </span><span style="color: #0000BB">myIterator</span><span style="color: #007700">;<br /><br />foreach(</span><span style="color: #0000BB">$it </span><span style="color: #007700">as </span><span style="color: #0000BB">$key </span><span style="color: #007700">=> </span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$key</span><span style="color: #007700">, </span><span style="color: #0000BB">$value</span><span style="color: #007700">);<br /> echo </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
something similar to:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
string(18) "myIterator::rewind"
string(17) "myIterator::valid"
string(19) "myIterator::current"
string(15) "myIterator::key"
int(0)
string(12) "firstelement"
string(16) "myIterator::next"
string(17) "myIterator::valid"
string(19) "myIterator::current"
string(15) "myIterator::key"
int(1)
string(13) "secondelement"
string(16) "myIterator::next"
string(17) "myIterator::valid"
string(19) "myIterator::current"
string(15) "myIterator::key"
int(2)
string(11) "lastelement"
string(16) "myIterator::next"
string(17) "myIterator::valid"
</pre></div>
</div>
</div>
</div>
</div>
<h2>Table of Contents</h2><ul class="chunklist chunklist_reference"><li><a href="iterator.current.html">Iterator::current</a> — Return the current element</li><li><a href="iterator.key.html">Iterator::key</a> — Return the key of the current element</li><li><a href="iterator.next.html">Iterator::next</a> — Move forward to next element</li><li><a href="iterator.rewind.html">Iterator::rewind</a> — Rewind the Iterator to the first element</li><li><a href="iterator.valid.html">Iterator::valid</a> — Checks if current position is valid</li></ul>
</div>
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