php forces download file implementation code

<?php 
$file = 'monkey.gif'; 

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; 
} 
?> 
?
<?php 
header("Content-Type: application/force-download"); 
header("Content-Disposition: attachment; filename=ins.jpg");  
readfile("imgs/test_Zoom.jpg"); 
?>