title: Modify DateTime object
body: <p>I create an object</p>
  
  <pre><code>$date = new DateTime();
  </code></pre>
  
  <p>It is set to current date <strong>2011-04-01 21:43:40</strong>. I try the following</p>
  
  <pre><code>$date-&gt;modify('midnight');
  </code></pre>
  
  <p>I expect the object to set to <strong>2011-04-01 00:00:00</strong>. But nothing happened. Object hadn't beed modified, and continue to have a <strong>2011-04-01 21:43:40</strong> date. I just want to reset the time to midnight (00:00:oo).</p>