title: Search array and return missing values
body: <p>I use this code to check if values exist in an array:</p>
  
  <pre><code>if (!in_array(array("Product code","Price","Supplier","Cost Price"), $data)) {
          die("You are missing fields");
       }
  </code></pre>
  
  <p>Works fine but I would like it to return the value that does not exist so if th array was  this:</p>
  
  <pre><code>$data = array("Price","Supplier","Cost Price");
  </code></pre>
  
  <p>PHP would return "Product code is not in array"</p>