我想通过在代码中静态提供数组来从省份下拉列表中选择省份来填充城市下拉列表

Question

我想通过从ddlProvisions中选择省份来显示城市。我如何在从ddl省选择的基础上获得这些城市？

public partial class Countries : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack == false)
{
string[] Provinces = { "Punjab", "Sindh", "NWFP", "KPK" };
ddlProvinces.DataSource = Provinces;
ddlProvinces.DataBind();

}
}
protected void ddlProvinces_SelectedIndexChanged(object sender, EventArgs e)
{
string[] PunjabCities = { "Lahore", "Sargodha", "Multan" };
string[] KPKCities = { "Peshawar", "Mardan", "Sawat" };
string[] SindhCities = { "Karachi", "Badin" };
string[] NWFPCities = { "Quetta", "Sibi" };

}
}

}

Answer 1

namespace WebApplication1
{
public partial class dropDown : System.Web.UI.Page
{
public String[] provinces;
public String[][] cities;
public dropDown()
{
provinces = new string[] { "Punjab", "KPK" };
cities = new string[][]
{
new string[] { "Sargodha", "Lahore", "Faisalabad" },
new string[] { "Peshawar", "Mardan", "Sawat" }
};
}
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack)
return;
province.DataSource = this.provinces;
province.DataBind();
province.SelectedValue = "Punjab";
city.DataSource = this.cities[0];
city.DataBind();
}
protected void province_SelectedIndexChanged(object sender, EventArgs e)
{
var element = (DropDownList)sender;
var selected = element.SelectedIndex;
city.DataSource = cities[selected];
city.DataBind();
}
}
}