title: Subtracting arrays to get every difference
body: <p>What I have</p>
  
  <pre><code>$array1 = [1,1,1];
  $array2 = [1,1];
  </code></pre>
  
  <p>What I'm doing:</p>
  
  <pre><code>array_diff( $array1, $array2 );
  </code></pre>
  
  <p>What I expected:</p>
  
  <pre><code>array(1) { 1 }
  </code></pre>
  
  <p>What I got</p>
  
  <pre><code>array(0) { }
  </code></pre>
  
  <p>How do I subtract two arrays to get every discrepancy?</p>
  
  <hr>
  
  <p>Edit:
  My example was incomplete, sorry.</p>
  
  <p>If we also have values like this:</p>
  
  <pre><code>$array1 = [1,1,2,1];
  $array2 = [1,1,1,2];
  </code></pre>
  
  <p>I would expect</p>
  
  <pre><code>[1,1,2,1] - [1,1,1,2] = []
  </code></pre>