title: What does array_walk() do?
body: <p>I don't get what <code>array_walk($arr, 'intval');</code> does, which I have commented out in the following code snippet:</p>
  
  <pre><code>&lt;?php    
  $handle = fopen ("php://stdin","r");
  fscanf($handle,"%d",$n);
  $arr_temp = fgets($handle);
  $arr = explode(" ",$arr_temp);
  //array_walk($arr,'intval');
  $sum=0;
  foreach($arr as $i)
  {
      $sum = $sum + $i;
  }
  echo $sum;
  ?&gt;
  </code></pre>
  
  <p>If I use it or not does not seem to change the output.</p>