title: Converting date (with milliseconds) into timestamp
body: <p>I have date format like <code>'25 May 2016 10:45:53:567'.</code></p>
  
  <p>I want to convert into the time stamp.</p>
  
  <p><code>strtotime</code> function returns empty.</p>
  
  <pre><code>$date = '25 May 2016 10:45:53:567';
  echo strtotime($date); 
  // returns empty
  </code></pre>
  
  <p>When I removed the milliseconds, it's working.</p>
  
  <pre><code>$date = '25 May 2016 10:45:53';
  echo strtotime($date);
  // returns 1464153353
  </code></pre>
  
  <p>Please sort out my issue. Thanks in advance.</p>