PHP file download code (compatible with multiple browsers, supports Chinese file names)

/**
* php file download example
* by bbs.it-home.org
*/
ob_start();
$ua = $_SERVER["HTTP_USER_AGENT"];
$filename ="Script Academy_File Download.doc";/ /Pay attention to transcoding
$encoded_filename = urlencode($filename);
//Compatible with various browsers
$encoded_filename = str_replace("+", "%20", $encoded_filename);
header('Content-Type: application /octet-stream');
if (preg_match("/MSIE/", $ua))
{
header('Content-Disposition: attachment; filename="'.urldecode($encoded_filename).'"');
}
else if (preg_match("/Firefox/", $ua))
{
header('Content-Disposition: attachment; filename*="gbk'''.$filename.'"');
}
 else
{
header('Content-Disposition: attachment; filename="'.$filename.'"');
}
ob_clean();
flush();
readfile($filename);
echo 'rnYou The downloaded file is provided by the Programmer's Home Editorial Department! Thank you for your download. ';
exit;
?>