Multiple selection in Check box list

CodeFile

using System;

using System.Collections;

using System.Configuration;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Xml.Linq;

public partial class CBList1 : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

       

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        String str = "";

        if (CheckBoxList1.Items[0].Selected == true)

            str = str + CheckBoxList1.Items[0];

        if (CheckBoxList1.Items[1].Selected == true)

            str = str + CheckBoxList1.Items[1];

        if (CheckBoxList1.Items[2].Selected == true)

            str = str + CheckBoxList1.Items[2];

        if (CheckBoxList1.Items[3].Selected == true)

            str = str + CheckBoxList1.Items[3];

        if (CheckBoxList1.Items[4].Selected == true)

            str = str + CheckBoxList1.Items[4];

        if (CheckBoxList1.Items[5].Selected == true)

            str = str + CheckBoxList1.Items[5];

        Response.Write("You have selected" + " " + str);

    }

}