title: PHP strtotime using m-d-Y format
body: <p>I have my dates in format (m-d-Y)  month-day-Year. I'm trying to subtract dates. I can't use strtotime() because it won't work in that format. How can I subtract dates with m-d-Y format?</p>
  
  <pre><code>&lt;?php
    date_default_timezone_set('America/Chicago');
  
    $olddate = "11-04-2013"; 
    $today = date("m-d-Y");
  
    $days = $olddate - $today;
  
    echo $days;
  
  ?&gt; 
  </code></pre>
  
  <p>If I use strtotime, my result (as of 11-05-2013) is "30". But I can't just divide by 30. If I change the olddate to "10-04-2013", then the result is also "30".</p>