private void export_to_excel()
    {
        try
        {
            //grd_detail.Visible = true;
            data_grid_print.Visible = true;
            Response.Clear();

            Response.AddHeader("content-disposition", "attachment;filename=Customerlist.xls");
            Response.Charset = "";
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            Response.ContentType = "application/vnd.xls";
            System.IO.StringWriter stringWrite = new System.IO.StringWriter();
            System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
            data_grid_print.RenderControl(htmlWrite);
            Response.Write(stringWrite.ToString());
            Response.End();
            data_grid_print.Visible = false;
            //grd_detail.Visible = false;
        }
        catch (Exception ex)
        {
        }
        finally
        {
        }

    }