title: PHP Pass by reference in foreach
body: <p>I have this code:</p>
  
  <pre><code>$a = array ('zero','one','two', 'three');
  
  foreach ($a as &amp;$v) {
  
  }
  
  foreach ($a as $v) {
    echo $v.PHP_EOL;
  }
  </code></pre>
  
  <p>Can somebody explain why the output is:
  zero one two two .</p>
  
  <p>From zend certification study guide.</p>