How to download file in PHP

Do you want to force users to download some files? If you say yes, you can look at source code below:

<?php
function download_file($archivo, $downloadfilename = null) {

if (file_exists($archivo)) {
 $downloadfilename = $downloadfilename !== null ? $downloadfilename : basename($archivo);
 header('Content-Description: File Transfer');
 header('Content-Type: application/octet-stream');
 header('Content-Disposition: attachment; filename=' . $downloadfilename);
 header('Content-Transfer-Encoding: binary');
 header('Expires: 0');
 header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
 header('Pragma: public');
 header('Content-Length: ' . filesize($archivo));

ob_clean();
 flush();
 readfile($archivo);
 exit;
 }
 }
 ?>

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