Prova così:
Codice PHP:
<?php
$cartella = opendir('./cartella_prova');
while ($file = readdir($cartella)) {
$file_array[] = $file;
sort($file_array);
}
foreach ($file_array as $file) {
if ( $file == ".." || $file == ".") {
continue;
}
echo "<center>";
echo "<a href=\"cartella_prova/$file\">$file</a>
";
echo "</center>";
}
?>