title: date_diff() expects parameter 2 to be DateTimeInterface, string given
body: <p>when i am trying to execute this getting error like   date_diff() expects parameter 2 to be DateTimeInterface, string given        </p>
  
  <pre><code>    $date2=date_create("2017-03-15");
      date_format($date2,"Y/m/d");
      $date1=date('Y/m/d');
      $diff=date_diff($date2,$date1);
      echo $diff;
  </code></pre>