จะทำลิงค์ดาวน์โหลดจากตัวแปรในภาษา PHP ต้องทำอย่างไรครับ

<td align="left"><a href="<?=$resul[file_content];?>"></a>&nbsp;</td>

<td align="left"><a href="<?=$resul[file_content];?>" target="_blank"><?=$resul[file_content];?></a></td>

echo 'FILE NAME : '.$_GET['filename'];
$file = $_GET['filename'];

if(file_exists($file)){
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename='.basename($file));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header('Pragma: public');
    header('Content-Length: '.filesize($file));
    ob_clean();
    flush();
    readfile($file);
    exit;
}