Export ASP.NET Grid to Excel

Below is the code for exporting the ASP.NET grid into Excel document

            HtmlForm form = new HtmlForm();
            string attachment = "attachment; filename=Employee.xls";
            Response.ClearContent();
            Response.AddHeader("content-disposition", attachment);
            Response.ContentType = "application/ms-excel";
            StringWriter stw = new StringWriter();
            HtmlTextWriter htextw = new HtmlTextWriter(stw);
            form.Controls.Add(GridView1);
            this.Controls.Add(form);
            form.RenderControl(htextw);
            Response.Write(stw.ToString());
            Response.End();