title: PHP unset array key for empty value not working
body: <p>For some reason I can not determine why empty array keys aren't being <code>unset</code>. Here is what I have...</p>
  
  <p><strong>PHP</strong></p>
  
  <pre><code>&lt;?php
  $attachments = explode('|',$_POST['post_attachments']);
  foreach($attachments as $k=&gt;$v)
  {
  echo 'k = \''.$v."'\n";
   if ($v=='')
   {
    unset($k);
   }
  }
  print_r($attachments);die();
  ?&gt;
  </code></pre>
  
  <p><strong>Output</strong></p>
  
  <blockquote>
    <p>k = ''</p>
    
    <p>k = 'secret_afound.gif'</p>
    
    <p>k = 'secret_aunlocked.gif'</p>
    
    <p>Array (</p>
  
  <pre><code>[0] =&gt; 
  [1] =&gt; secret_afound.gif
  [2] =&gt; secret_aunlocked.gif
  </code></pre>
    
    <p>)</p>
  </blockquote>