if($_GET['change']=="up"){
if($_POST['file'] != null)
{
$avatar=$_SESSION['valid_user'];
$avatar2 = end(explode(".", $_FILES['file']['name']));
$avatar .= ".";
$avatar .= $avatar2[1];
echo $avatar;
$maxsize=256214;
if($_FILES['file']['name'] <= $maxsize)
{...