title: Add hours in a date in PHP
body: <p>Want to add hours in a date .
  Please help.</p>
  
  <p>The PHP code is:</p>
  
  <pre><code>$createdDate=date_create("2013-03-17 07:11:00");
  $hour = 4;
  </code></pre>
  
  <p>I tried using strtotime. But it gives an error.</p>
  
  <p>Thanks</p>