title: Check for unallowed keys in an array?
body: <p>What is the best way to check if an array contains unallowed keys ?</p>
  
  <pre><code>$array = array("Apple" =&gt; 33, "Orange" =&gt; 22, "Dogs" =&gt; 77,);
  
  $allowed = array("Apple", "Orange");
  </code></pre>
  
  <p>Desired output is:</p>
  
  <pre><code>if (!something($array,$allowed)){echo 'Unallowed data';}
  </code></pre>
  
  <p>Thanks</p>