<?php
class Uploaded {
    private $field_name = '';
    // $field_name is the name of the input in uploading form
    public function __construct($field_name) {
        $this -> field_name = $field_name;
    }
    // $path is the path to the directory where
    // the uploaded file you want stored.
    // $primary_name is the primary part of the
    // file name you want the new name of the uploaded file to be
    // such as 'song' with 'song.mp3'. The extensions part of the
    // new name will be determined from that of the uploaded one.
    public function getFileName($path, $primary_name = '') {
        if (empty($path)) {
            return false;
        }
        if (empty($primary_name)) {
            // Use microtime() as temporary file name if no $primary_name is given
            $primary_name = microtime();
        }
        if (is_uploaded_file($_FILES[$this -> field_name]['tmp_name'])) {
            $client_name = basename($_FILES[$this -> field_name]['name']);
            $ext = substr($client_name, strrpos($client_name, '.'));
            $server_name = $primary_name.$ext;
            if (file_exists($path.$server_name)) {
                // deleting any existing files with the same name here
                // so that the old file can be updated this way.
                unlink($path.$server_name);
            }
            if (move_uploaded_file($_FILES[$this -> field_name]['tmp_name'], $path.$server_name)) {
                // The new name of the uploaded file will be returned
                // for access and retrieval of it.
                return $server_name;
            }
        }
        return false;
    }
}
?>

<form enctype="multipart/form-data" method="post" action="upload.php">
    <input type="file" name="photo" />
    <button type="submit" name="submit">Submit</button>
</form>

<?php
require_once('Uploaded.class.php');
if (isset($_POST['submit'])) {
    $myPhoto = new Uploaded('photo');
    $photoFileName = $myPhoto -> getFileName('uploaded/photos/', 'new_name');
}
?>