title: claculate the number of days between two dates without libraries
body: <p>I need to claculate the number of days between two dates without using any date or calendar classes provided by any library.</p>
  
  <p>Here's my idea:</p>
  
  <pre><code>numberOfDays =  Math.abs((toYear - fromYear) * 365);
  numberOfDays = numberOfDays + Math.abs((toMonth - fromMonth) * 12);
  numberOfDays = numberOfDays + Math.abs((toDay - fromDay));
  </code></pre>
  
  <p>Thoughts?</p>