title: How to compare times as strings in the format "HH:MM:SS"?
body: <p>How to check if the user is on time.</p>
  <p>Example:
  The program starts at 13:50:00, and ends at 14:50:00.</p>
  <p>And if a user logs in, and his time is 14:30:00, he can log in.
  If he comes in again at 14:55:00 he can't come in again.</p>