title: php date() and expiration date()
body: <p>I am creating an application in PHP that will allow the user to create  a 'post' that initially lasts for 7 days and the user can add increments of 7 days at any time. I ran into a snag in working with the php date('Y-m-d H:i:s') function and adding days to an already established start date that is pulled from the datebase after the 'post' has been initiated... </p>
  
  <pre><code>$timestamp = "2016-04-20 00:37:15";
  $start_date = date($timestamp);
  
  $expires = strtotime('+7 days', $timestamp);
  //$expires = date($expires);
  
  $date_diff=($expires-strtotime($timestamp)) / 86400;
  
  echo "Start: ".$timestamp."&lt;br&gt;";
  echo "Expire: ".$expires."&lt;br&gt;";
  
  echo round($date_diff, 0)." days left";
  </code></pre>
  
  <p>That is what I have so far and it's not doing very much for me. Could anyone show me an example of the right way to do this?</p>