header("Pragma: public");

header("Expires: 0");

header("Expires: 0");

header("Cache-Control:must-revalidate, post-check=0, pre-check=0");

header("Content-Type:application/force-download");

header("Content-Type:application/vnd.ms-execl;charset=utf-8");

header("Content-Type:application/octet-stream");

header("Content-Type:application/download");

header('Content-Disposition:attachment;filename='.$filename);

header("Content-Transfer-Encoding:binary");