asp.net - Getting error to generate pdf -

 protected void txt_btn_click(object sender, eventargs e) {     response.contenttype = "application/pdf";     response.addheader("content-disposition", "attachment;filename=testresult.pdf");     response.cache.setcacheability(httpcacheability.nocache);      stringbuilder htmltext = new stringbuilder();     htmltext.append("<table style='color:red;' border='1'><tr><th>createing pdf</th><tr><td> abcdef</td></tr></table>");      stringreader stringreader = new stringreader(htmltext.tostring());     document doc = new document(pagesize.a4);     list<itextsharp.text.ielement> elements =             itextsharp.text.html.simpleparser.htmlworker.parsetolist(stringreader, null);     doc.open();     foreach (object item in elements)     {         doc.add((ielement)item);     }     doc.close();     // response output     pdfwriter.getinstance(doc, response.outputstream);     doc.open();      //doc.close();      response.write("pdf created"); } 

}

i try create pdf file.but pdf created 0kb.mean when open it's shw error may pdf damaged

i'm assuming using itextsharp library.

private void generatepdf()     {         try         {             string pdfpath = "~/pdf/file_1.pdf";             stringbuilder sb = new stringbuilder();             sb.append("name : chamara" + environment.newline);             sb.append("address : sri lanaka" + environment.newline);             sb.append("institute : sliit" + environment.newline);             document doc = new document();             pdfwriter.getinstance(doc, new filestream(server.mappath(pdfpath), filemode.create));             doc.open();             doc.add(new paragraph(sb.tostring()));             doc.close();          }         catch (exception ex)         {             throw ex;         }     }