DialogResult dr = MessageBox.Show("是否要繼續(xù)嗎？", "警告！?。?, MessageBoxButtons.OKCancel);//它彈出的對(duì)話框如下圖所示
if (dr == DialogResult.OK)//只有按下確定按鈕才執(zhí)行下面
{
label1.Text = "天氣不錯(cuò)";
}

public Form1()// Form1的構(gòu)造函數(shù)
{
InitializeComponent();
AreaDataBind(comboBox1, "0001");
AreaDataBind(comboBox2, comboBox1.SelectedValue.ToString());
AreaDataBind(comboBox3, comboBox2.SelectedValue.ToString());
}
public void AreaDataBind(ComboBox cb, string Pcode)
{
cb.DataSource = new ChinaData().Select(Pcode);//數(shù)據(jù)源
cb.DisplayMember = "AreaName";//顯示值
cb.ValueMember = "AreaCode";//實(shí)際值
}
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
AreaDataBind(comboBox2, comboBox1.SelectedValue.ToString());
}
private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
{
AreaDataBind(comboBox3, comboBox2.SelectedValue.ToString());
}