How to Export Data to Excel from a DataSet

protected void btntoExcel_Click(object sender, EventArgs e)
{
    ds = rs.onemindelayeduser("selectall", 0, "", "", "", "", "", "");
    if (ds != null)
    {
        if (ds.Tables[0].Rows.Count > 0)
        {
            DataTable dt = ds.Tables[0];
            dt.Columns.Remove("srno");
            string attachment = "attachment; filename=users.xls";
            Response.ClearContent();
            Response.AddHeader("content-disposition", attachment);
            Response.ContentType = "application/vnd.ms-excel";
            string tab = "";
            foreach (DataColumn dc in dt.Columns)
            {
                Response.Write(tab + dc.ColumnName);
                tab = "\t";
            }
            Response.Write("\n");
            int i;
            foreach (DataRow dr in dt.Rows)
            {
                tab = "";
                for (i = 0; i < dt.Columns.Count; i++)
                {
                    Response.Write(tab + dr[i].ToString());
                    tab = "\t";
                }
                Response.Write("\n");
            }
            Response.End();
        }
    }
}