title: Opposite of array_intersect
body: <p>I'm looking for the opposite of the function <code>array_intersect</code>, basically a function that returns the element that are <strong>not</strong> present in <strong>each</strong> of the provided arrays. </p>
  
  <p>Example:</p>
  
  <pre><code>$a1 = array(1, 2, 3);
  $a2 = array(2, 3, 4);
  $result = array(1, 4);
  </code></pre>
  
  <p>I know how to do it programmatically (I just have two array so <code>array_merge(array_diff($a1, $a2), array_diff($a2, $a1))</code> would do the job), but I'd like to know whether there's a built-in function that I can't find.</p>
  
  <p>Thanks.</p>