WINFORM Combox下拉框级联

已省、市下拉框级联关系作为例子

private void Form1_Load(object sender, EventArgs e)
        {
            ComPro.DataSource = new string[] { "河南", "山东", "安徽" };

        }
        private void ComPro_SelectedIndexChanged(object sender, EventArgs e)
        {
            string[][] cityStr = { new string[]{ "商丘", "郑州", "开封" }, new string[]{ "菏泽", "威海", "青岛" }, new string[]{ "合肥", "亳州", "徐州" } };
            switch (ComPro.SelectedIndex)
            {
                case 1:
                    comCity.DataSource = cityStr[ComPro.SelectedIndex];
                    break;
                case 2:
                    comCity.DataSource = cityStr[ComPro.SelectedIndex];
                    break;
                case 3:
                    comCity.DataSource = cityStr[ComPro.SelectedIndex];
                    break;
            }