在ASP.NET中找到10月的最后一个星期日c#

using System;

class Program
{
    static void Main()
    {
        DateTime lastSunday = FindLastSundayOfMonth(10, 2021);
        Console.WriteLine("The last Sunday of October 2021 is: " + lastSunday.ToString("dddd, MMMM dd, yyyy"));
    }

    static DateTime FindLastSundayOfMonth(int month, int year)
    {
        DateTime lastDayOfMonth = new DateTime(year, month, DateTime.DaysInMonth(year, month));
        DateTime lastSundayOfMonth = lastDayOfMonth.AddDays(-(int)lastDayOfMonth.DayOfWeek);

        if (lastSundayOfMonth.Month == month)
        {
            return lastSundayOfMonth;
        }
        else
        {
            return lastSundayOfMonth.AddDays(-7);
        }
    }
}