What are the potential syntax errors in the provided PHP code for downloading a file?

The potential syntax errors in the provided PHP code for downloading a file include missing semicolons at the end of lines, incorrect variable names, and missing closing PHP tags. To solve these issues, ensure that all lines end with a semicolon, use correct variable names, and close the PHP tags properly.

<?php
$file = 'example.txt';

if (file_exists($file)) {
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename="'.basename($file).'"');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    readfile($file);
    exit;
} else {
    echo 'File not found.';
}
?>