title: Extract timestamp from filename and sort
body: <p>I'm trying to look through each item in a folder and add each item to an array sorted by the datestamp in the filename.</p>
  
  <p>For example, I have three files:</p>
  
  <ul>
  <li>myfile_20150813_040949.txt</li>
  <li>myfile_20150812_030949.txt</li>
  <li>myfile_20150812_010949.txt</li>
  </ul>
  
  <p>I'm not sure how to parse out the time from each and add them to an array in ascending order. Any help would be appreciated.</p>