Answer by Eduardo Pelais for Difference in months between two dates

My problem was solved with this solution:

static void Main(string[] args)        {            var date1 = new DateTime(2018, 12, 05);            var date2 = new DateTime(2019, 03, 01);            int CountNumberOfMonths() => (date2.Month - date1.Month) + 12 * (date2.Year - date1.Year);            var numberOfMonths = CountNumberOfMonths();            Console.WriteLine("Number of months between {0} and {1}: {2} months.", date1.ToString(), date2.ToString(), numberOfMonths.ToString());            Console.ReadKey();            //            // *** Console Output:            // Number of months between 05/12/2018 00:00:00 and 01/03/2019 00:00:00: 3 months.            //        }