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<title>The Traversable interface</title>
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<h1 class="title">The Traversable interface</h1>
<div class="partintro"><p class="verinfo">(PHP 5 >= 5.0.0)</p>
<div class="section" id="traversable.intro">
<h2 class="title">Introduction</h2>
<p class="para">
Interface to detect if a class is traversable using <a href="control-structures.foreach.html" class="link">foreach</a>.
</p>
<p class="para">
Abstract base interface that cannot be implemented alone. Instead it must
be implemented by either <a href="class.iteratoraggregate.html" class="classname">IteratorAggregate</a> or
<a href="class.iterator.html" class="classname">Iterator</a>.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Internal (built-in) classes that implement this interface can be used in
a <a href="control-structures.foreach.html" class="link">foreach</a> construct and do not need to implement
<a href="class.iteratoraggregate.html" class="classname">IteratorAggregate</a> or
<a href="class.iterator.html" class="classname">Iterator</a>.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
This is an internal engine interface which cannot be implemented in PHP
scripts. Either <a href="class.iteratoraggregate.html" class="classname">IteratorAggregate</a> or
<a href="class.iterator.html" class="classname">Iterator</a> must be used instead.
When implementing an interface which extends Traversable, make sure to
list <a href="class.iteratoraggregate.html" class="classname">IteratorAggregate</a> or
<a href="class.iterator.html" class="classname">Iterator</a> before its name in the implements
clause.
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</p></blockquote>
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<div class="section" id="traversable.synopsis">
<h2 class="title">Interface synopsis</h2>
<div class="classsynopsis">
<div class="ooclass"></div>
<div class="classsynopsisinfo">
<span class="ooclass">
<strong class="classname">Traversable</strong>
</span>
{</div>
}</div>
<p class="para">
This interface has no methods, its only purpose is to be the base
interface for all traversable classes.
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