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

public Form1()// Form1的構造函數{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);//數據源cb.DisplayMember = "AreaName";//顯示值cb.ValueMember = "AreaCode";//實際值}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());}