private void TxtDays_TextChanged(object sender, EventArgs e)
        {
            Regex nonNumericRegex = new Regex(@"\D");

            if (!nonNumericRegex.IsMatch(TxtDays.Text) && TxtDays.Text != String.Empty)
            {
                DtpDateTo.Value = DtpDateFrom.Value.AddDays(Convert.ToInt32(TxtDays.Text));
            }
            else if (TxtDays.Text != String.Empty)
            {
                TxtDays.Text = TxtDays.Text.Remove(TxtDays.Text.Length - 1, 1);
                TxtDays.Select(TxtDays.Text.Length, 0);
            }
        }
 private void BtnClear_Click(object sender, EventArgs e)
 {
     TxtTcnumber.Clear();
     TxtName.Clear();
     TxtSurname.Clear();
     TxtAddress.Clear();
     TxtDays.Clear();
     MskTxtPhoneNumber.Clear();
     TxtEmail.Clear();
     TxtPayment.Clear();
     TxtRoomNumber.Clear();
     dateTimePicker1.ResetText();
     DtpCheckin.ResetText();
     DtpCheckout.ResetText();
 }