Export cellset grid report

protected void ExportToExcel(object sender, EventArgs e)

    {



        string attachment = "attachment; filename=myExcelSheet_" + DateTime.Now.ToString() + ".xls";

        Response.ClearContent();

        Response.AddHeader("content-disposition", attachment);

        Response.ContentType = "application/ms-excel";

        StringWriter sw = new StringWriter();

        HtmlTextWriter htw = new HtmlTextWriter(sw);

        // hide private columns if any

        GridView1.Columns[0].Visible = false;

        GridView1.Columns[12].Visible = false;

        GridView1.Columns[19].Visible = false;



        GridView1.RenderControl(htw);

        Response.Write(sw.ToString());

        Response.End();



    }