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    copied!<p>Some points to note when working with <code>foreach()</code>:</p> <p>a) <code>foreach</code> works on the <strong>prospected copy</strong> of the original array. It means foreach() will have SHARED data storage until or unless a <code>prospected copy</code> is not created <a href="http://php.net/manual/en/control-structures.foreach.php" rel="noreferrer">foreach Notes/User comments</a>.</p> <p>b) What triggers a <strong>prospected copy</strong>? Prospected copy is created based on the policy of <code>copy-on-write</code>, that is, whenever an array passed to foreach() is changed, a clone of original array is created.</p> <p>c) The original array and foreach() iterator will have <code>DISTINCT SENTINEL VARIABLES</code>, that is, one for the original array and other for foreach; see the test code below. <a href="http://php.net/manual/en/book.spl.php" rel="noreferrer">SPL</a> , <a href="http://www.php.net/manual/en/spl.iterators.php" rel="noreferrer">Iterators</a>, and <a href="http://www.php.net/manual/en/class.arrayiterator.php" rel="noreferrer">Array Iterator</a>.</p> <p>Stack&nbsp;Overflow question <em><a href="https://stackoverflow.com/questions/2728709">How to make sure the value is reset in a 'foreach' loop in PHP?</a></em> addresses the cases (3,4,5) of your question.</p> <p>The following example show that each() and reset() DOES NOT affect <code>SENTINEL</code> variables <code>(for example, the current index variable)</code> of the foreach() iterator.</p> <pre><code>$array = array(1, 2, 3, 4, 5); list($key2, $val2) = each($array); echo "each() Original (outside): $key2 =&gt; $val2&lt;br/&gt;"; foreach($array as $key =&gt; $val){ echo "foreach: $key =&gt; $val&lt;br/&gt;"; list($key2,$val2) = each($array); echo "each() Original(inside): $key2 =&gt; $val2&lt;br/&gt;"; echo "--------Iteration--------&lt;br/&gt;"; if ($key == 3){ echo "Resetting original array pointer&lt;br/&gt;"; reset($array); } } list($key2, $val2) = each($array); echo "each() Original (outside): $key2 =&gt; $val2&lt;br/&gt;"; </code></pre> <p><strong>Output:</strong></p> <pre><code>each() Original (outside): 0 =&gt; 1 foreach: 0 =&gt; 1 each() Original(inside): 1 =&gt; 2 --------Iteration-------- foreach: 1 =&gt; 2 each() Original(inside): 2 =&gt; 3 --------Iteration-------- foreach: 2 =&gt; 3 each() Original(inside): 3 =&gt; 4 --------Iteration-------- foreach: 3 =&gt; 4 each() Original(inside): 4 =&gt; 5 --------Iteration-------- Resetting original array pointer foreach: 4 =&gt; 5 each() Original(inside): 0=&gt;1 --------Iteration-------- each() Original (outside): 1 =&gt; 2 </code></pre>
 

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