private void btn_addInfant1_Click(object sender, EventArgs e)
 {
     try
     {
         if (panel4.Controls.OfType <TextBox>().Any(x => x.ForeColor == Color.Red || x.Text == ""))
         {
             throw new Exception("Please fill all details correctly");
         }
         if (comboBox4.SelectedIndex < 0)
         {
             throw new Exception("Please select nationality");
         }
         var genderButton = panel4.Controls.OfType <Button>().FirstOrDefault(x => x.BackColor == Color.RoyalBlue);
         if (genderButton == null)
         {
             throw new Exception("Please choose Gender");
         }
         int gender = (genderButton.Text == "MALE") ? 1 : 2;
         if (birthdate == "")
         {
             throw new Exception("Please fill Birthdate");
         }
         Infant inf = new Infant((textBoxName.Text + " " + textBoxSurname.Text), textBoxPassport.Text,
                                 (Citizenship)comboBox4.SelectedIndex, dateTimePicker1.Value, (Gender)gender);
         DataBase.InfantList.Add(inf);
         Close();
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
     }
 }
 public Passenger(string fullname, string passportNo, Citizenship citizen,
                  DateTime birth, Gender sex)
 {
     Fullname    = fullname;
     PassportNo  = passportNo;
     Citizenship = citizen;
     BirthDate   = birth;
     Gender      = sex;
     PaymentCard = null;
     Infant      = null;
 }