title: hh:mm:ss difference return wrong answer in php
body: <p>I am using this code to calculate the time period. In fact, I want the period between two HH:MM:SS moment and have a result in HH:MM:SS format.</p>
  
  <pre><code>$time1 = strtotime('00:00:00');
  $time2 = strtotime('00:00:07');
  $diff = $time2 - $time1;
  $diff = date('H:i:s', $diff);
  </code></pre>
  
  <p>I'm expecting <code>00:00:07</code> but I get <code>01:00:07</code>. What could be the problem?</p>
  
  <p>Irvin run <a href="https://eval.in/684340" rel="nofollow noreferrer">here</a>, and get right answer but I run the same code on my local machine and wrong!!
  Is it timezone or maybe some configuration effect the result?!</p>