تمرین نمایش تاریخ - کنترل توسط سازنده

 private void btnTime_Click(object sender, EventArgs e)
 {
     if (cbDay.Text != "" || cbMonth.Text != "" || cbYear.Text !="")
     {
         string selectedDay = cbDay.Text;
         string selectedMonth = cbMonth.Text;
         string selectedYear = cbYear.Text;
         TimeShow time = new TimeShow(selectedDay, selectedMonth, selectedYear);
         lblTime.Text = $"تاریخ انتخابی شما برابر می باشد با {time.Day} {time.Month}" +
             $" {time.Year}";
     }
     else
     {
         MessageBox.Show("لطفا تمام اطلاعات را وارد کنید!!");
     }
 }

 private void cbMonth_SelectedIndexChanged(object sender, EventArgs e)
 {
     int selectDay = int.Parse(cbDay.Text);
     int selectMonth = int.Parse(cbMonth.Text);
     cbDay.ForeColor = Color.Black;
     if (selectMonth > 6)
     {
         if (selectDay > 30)
         {
             MessageBox.Show("لطفا روز را درست انتخاب کنید!");
             //cbDay.BackColor = Color.Red;
             cbDay.ForeColor = Color.Red;
         }
     }
     else
     {
         cbDay.BackColor = Color.White;
     }
 }

 private void cbDay_SelectedIndexChanged(object sender, EventArgs e)
 {
     if(cbMonth.Text!="")
     {
         int selectDay = int.Parse(cbDay.Text);
         int selectMonth = int.Parse(cbMonth.Text);
         cbDay.ForeColor = Color.Black;
         if (selectMonth > 6)
         {
             if (selectDay > 30)
             {
                 MessageBox.Show("لطفا روز را درست انتخاب کنید!");
                 //cbDay.BackColor = Color.Red;
                 cbDay.ForeColor = Color.Red;
             }
         }
         else
         {
             cbDay.BackColor = Color.White;
         }
     }
 }
 ==================================================================
  internal class TimeShow
 {
     public string Day { get; }
     public string Month { get; }
     public string Year { get; }
     public TimeShow(string day, string month, string year)
     {
         switch (day)
         {
             case "01":
                 {
                     Day = "یکم";
                     break;
                 }
             case "02":
                 {
                     Day = "دوم";
                     break;
                 }
             case "03":
                 {
                     Day = "سوم";
                     break;
                 }
             case "04":
                 {
                     Day = "چهارم";
                     break;
                 }
             case "05":
                 {
                     Day = "پنجم";
                     break;
                 }
             case "06":
                 {
                     Day = "ششم";
                     break;
                 }
             case "07":
                 {
                     Day = "هفتم";
                     break;
                 }
             case "08":
                 {
                     Day = "هشتم";
                     break;
                 }
             case "09":
                 {
                     Day = "نهم";
                     break;
                 }
             case "10":
                 {
                     Day = "دهم";
                     break;
                 }
             case "11":
                 {
                     Day = "یازدهم";
                     break;
                 }
             case "12":
                 {
                     Day = "دوازدهم";
                     break;
                 }
             case "13":
                 {
                     Day = "سیزدهم";
                     break;
                 }
             case "14":
                 {
                     Day = "چهاردهم";
                     break;
                 }
             case "15":
                 {
                     Day = "پانزدهم";
                     break;
                 }
             case "16":
                 {
                     Day = "شانزدهم";
                     break;
                 }
             case "17":
                 {
                     Day = "هفدهم";
                     break;
                 }
             case "18":
                 {
                     Day = "هجدهم";
                     break;
                 }
             case "19":
                 {
                     Day = "نوزدهم";
                     break;
                 }
             case "20":
                 {
                     Day = "بیستم";
                     break;
                 }
             case "21":
                 {
                     Day = "بیست ویکم";
                     break;
                 }
             case "22":
                 {
                     Day = "بیست و دوم";
                     break;
                 }
             case "23":
                 {
                     Day = "بیست و سوم";
                     break;
                 }
             case "24":
                 {
                     Day = "بیست و جهارم";
                     break;
                 }
             case "25":
                 {
                     Day = "بیست و پنجم";
                     break;
                 }
             case "26":
                 {
                     Day = "بیست و ششم";
                     break;
                 }
             case "27":
                 {
                     Day = "بیست و هفتم";
                     break;
                 }
             case "28":
                 {
                     Day = "بیست و هشتم";
                     break;
                 }
             case "29":
                 {
                     Day = "بیست و نهم";
                     break;
                 }
             case "30":
                 {
                     Day = "سی ام";
                     break;
                 }
             case "31":
                 {
                     Day = "سی و یکم";
                     break;
                 }
         }
         switch (month)
         {
             case "01":
                 {
                     Month = "  فروردین ماه";
                     break;
                 }
             case "02":
                 {
                     Month = "اردیبهشت ماه";
                     break;
                 }
             case "03":
                 {
                     Month = "خرداد ماه";
                     break;
                 }
             case "04":
                 {
                     Month = "تیر ماه";
                     break;
                 }
             case "05":
                 {
                     Month = "مرداد ماه";
                     break;
                 }
             case "06":
                 {
                     Month = "شهریور ماه";
                     break;
                 }
             case "07":
                 {
                     Month = "مهر ماه";
                     break;
                 }
             case "08":
                 {
                     Month = "آبان ماه";
                     break;
                 }
             case "09":
                 {
                     Month = "آذر ماه";
                     break;
                 }
             case "10":
                 {
                     Month = "دی ماه";
                     break;
                 }
             case "11":
                 {
                     Month = "بهمن ماه";
                     break;
                 }
             case "12":
                 {
                     Month = "اسفند ماه";
                     break;
                 }
         }
         switch (year)
         {
             case "1404":
                 {
                     Year = "چهارصدوچهار";
                     break;
                 }
             case "1405":
                 {
                     Year = "چهارصدوپنج";
                     break;
                 }
             case "1406":
                 {
                     Year = "چهارصدوشش";
                     break;
                 }
             case "1407":
                 {
                     Year = "چهارصدوهفت";
                     break;
                 }
             case "1408":
                 {
                     Year = "چهارصدوهشت";
                     break;
                 }
         }
     }
 }