کنترل کامبوباکس-combobox

  private void button1_Click(object sender, EventArgs e)
        {
            int roztav, mahtav, saltav, emroz, inmah, emsal, roz, mah, sal;
            emroz = Convert.ToInt32(comday.Text);
            inmah = commonth.SelectedIndex + 1;
            emsal = Convert.ToInt32(comyear.Text);
            //--------------------------------
            roztav = Convert.ToInt32(comdaytav.Text);
            mahtav = commonthtav.SelectedIndex + 1;
            saltal = Convert.ToInt32(comyeartav.Text);
            //--------------------------------
            roz = emroz - roztav;
            mah = inmah - mahtav;
            sal = emsal - saltal;
            //--------------------------------
            if (roz < 0)
            {
                mah--;
                roz += 30;
	}

            txtday.Text = roz.ToString();
            txtmonth.Text = mah.ToString();
            txtyear.Text = sal.ToString();
        }