export gridview data to pdf file

Response.ContentType = "application/pdf";
       Response.AddHeader("content-disposition", "attachment;filename=GridViewExport.pdf");
       Response.Cache.SetCacheability(HttpCacheability.NoCache);
       StringWriter sw = new StringWriter();
       HtmlTextWriter hw = new HtmlTextWriter(sw);
       grdVendorList.AllowPaging = false;
       grdVendorList.DataBind();
       grdVendorList.RenderControl(hw);
       StringReader sr = new StringReader(sw.ToString());
       Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);
       HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
       PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
       pdfDoc.Open();
       htmlparser.Parse(sr);
       pdfDoc.Close();
       Response.Write(pdfDoc);
       Response.End();