title: How can I generate a list of datetime intervals that are in between two dates?
body: <p>Let's suppose I have an interval. Say 15 minutes.</p>
  
  <p>I have a start time of 13:57 and an end time of 15:17.</p>
  
  <p>The time when this process runs happens to be 14:07.</p>
  
  <p>I want the result to be 14:00,14:15,14:30,14:45,15:00,15:15 while retaining the year/month/date, etc.</p>
  
  <p>So far, I have these facts down. The minutes modulo the interval is always zero. I need to count down from the current time until I hit the first mod-zero number which is 14:00. </p>
  
  <p>I then simply increase that number by the interval until I reach my ceiling. My real question is how to come up with an elegant, simple way to find this first floor number.</p>
  
  <p>The interval is a timespan and the other two values are datetimes.</p>
  
  <p>Any ideas?</p>