Create excel and zip without save file and images using asp.net

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public void ExportToExcel(DataTable dt, string FIleName)

        {

            StringBuilder sb = new StringBuilder();

            sb.Append("");

            string Fullfilename = "" + FIleName + DateTime.Now.ToString("dd_MM_yyyy_hh_mm_ss") + ".xls";

            String HeaderStyle = "border:.3pt solid windowtext; font-weight:700;   word-wrap: normal; word-break: break-all; ";

            sb.Append("<table width='70%'>");

            sb.Append("<tr style='"+ HeaderStyle + "'>");

            string[] Heads = { "ID", "Name", "Address" };

            for (int j = 0; j < 2; j++)

            {

                sb.Append("<th>"+ Heads [j]+ "</th>");

            }

            sb.Append("</tr>");

            String RowStyle = "border:.1pt solid windowtext; font-weight:100; font-size:9pt;rowspan=2;";

         

            for (int j = 0; j < 5; j++)

            {

                sb.Append("<tr style='" + RowStyle + "'>");

                for (int i = 0; i < 2; i++)

                {

                    sb.Append("<td>" + "Name_"+j+"_"+i + "</td>");

                }              

                sb.Append("</tr>");

            }

          

            sb.Append("</table>");

            MemoryStream stream = new MemoryStream();

            byte[] data = Encoding.ASCII.GetBytes(sb.ToString());

            stream.Write(data, 0, data.Length);

            stream.Seek(0, SeekOrigin.Begin);

            HttpResponse Response = HttpContext.Current.Response;

            Response.ClearHeaders();

            Response.Charset = "UTF-8";

            string filePath = string.Empty;

            using (Ionic.Zip.ZipFile zip = new Ionic.Zip.ZipFile())

            {

                zip.AddEntry(Fullfilename, stream);

                zip.AlternateEncodingUsage = Ionic.Zip.ZipOption.AsNecessary;

                zip.AddDirectoryByName("UserDocs");

                string pth = Server.MapPath("~/FolderName");

                DirectoryInfo dir = new DirectoryInfo(pth);

                for (int i = 0; i < dt.Rows.Count; i++)

                {

                    foreach (var d in dir.GetFiles())

                    {

                        if (d.Name == Convert.ToString(dt.Rows[i]["ImageName"]))

                        {

                            string pt = pth + "\\" + d.Name;

                            zip.AddFile(d.FullName, "UserDocs");

                        }

                    }

                }

                Response.Clear();

                Response.BufferOutput = false;

                string fName =DateTime.Now.ToString("yyyy-MMM-dd-HHmmss");

                Response.ContentType = "application/zip";

                Response.AddHeader("content-disposition", "attachment; filename=" + fName +".zip";

                zip.Save(Response.OutputStream);

                Response.End();

            }

        }