get control from grdview

private void DGV_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
    {
    comboBOX = (ComboBox)e.Control;
    comboBOX .SelectedIndexChanged -=new EventHandler(comboBOX _SelectedIndexChanged);
    comboBOX .SelectedIndexChanged +=new EventHandler(comboBOX _SelectedIndexChanged);
    }
    private void comboBOX _SelectedIndexChanged(object sender, EventArgs e)
    {
    ComboBox combo = sender as ComboBox;
    string str=combo.SelectedIndex.ToString();
    }