Sort folders by their modification date instead of alphabetic order.

sort_folder.php

<?php
$folder = "files/";
$handle = opendir($folder);

# Making an array containing the files in the current directory:
while ($file = readdir($handle)){   
    if( $file != ".." && $file != "." ){
        $key = filemtime($file);
        $files[$key] = $file ;
    }
}
closedir($handle);
// sort files by mtime:
ksort($files) ;

#echo the files
foreach ($files as $file) {
    echo "<a href=$folder$file target='read'>$file</a>"."<br />" ;
}
?>