using System;

public class Program

{

    static DateTime now = new DateTime(2019,7,31).AddHours(23).AddMinutes(59).AddSeconds(58);

    public static void Main()

    {

            DateTime exp = new DateTime(2019, 7,DateTime.DaysInMonth(2019, 7));

    Console.WriteLine("exp date:" + exp);

    bool valid = IsCardValid(exp);

    Console.WriteLine("isValid:" + valid);

    }

     private static bool IsCardValid(DateTime date)

 {

            DateTime expDate = new DateTime(date.Year, date.Month, DateTime.DaysInMonth(date.Year, date.Month)).AddHours(23).AddMinutes(59).AddSeconds(59);

            Console.WriteLine("expdate:" + expDate);

​

            return expDate >now;  //DateTime.Now;

}

}