DateTime różnica dni

 protected int GetDifferenceDays(DateTime b)
        {
            DateTime a = DateTime.Now;
            TimeSpan diffResult = b.Subtract(a);

            int d = (int)diffResult.TotalDays;
            return d;
        }

static protected int GetDifferenceDays(DateTime b)
{
    return (int)(b.Date - DateTime.Now.Date).TotalDays;
}