protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
string[,] booklist ={
{"001","C# 3.0"},
{"002","ASP.NET3.5"},
{"003","三国演义"},
{"004","水浒"},
{"005","西游记"}
};
for (int i = 0; i < booklist.GetLength(0); i++)
{
// DrowdownList只能显示二维数组中的一个维度,这里显示的是书名
ddlBooks.Items.Add(new ListItem(booklist[i, 1], booklist[i, 0]));
}

}
}

protected void ddlBooks_SelectedIndexChanged(object sender, EventArgs e)
{
if (ddlBooks.SelectedIndex != -1)
{
lblBooks.Text = string.Format
("书名：{0},号码：{1}", this.ddlBooks.SelectedItem.Text,

this.ddlBooks.SelectedValue);
}
}