How to count the Number of days between two dates?

Try:

            DateTime dt1 = new DateTime(2012, 7, 1);
            DateTime dt2 = DateTime.Today;
            double days = (dt2 - dt1).TotalDays;
            Console.WriteLine(days); // 22

Add 1 to 'days' if you want it to be inclusive of both end points.

If you're not interested in fractional days, you can use the Days rather than the TotalDays property.