function cube($n)
{
    return ($n * $n * $n);
}

$a = [1, 2, 3, 4, 5];
$array = array_map('cube', $a);
print_r($array);

$file="05-readfile.php";

if (file_exists($file))
	echo readfile($file);

echo $_REQUEST['action']
?>

<form action="05-sample.php" method="post">
<input type="hidden" name="action" value="form">
<input type="submit" />
</form>