Codeigniter 3 with upload not working

PHP Code:

#controller
parent::__construct();
    $this->load->library('upload');

#library/upload
class upload
{ 
$config['upload_path'] = './uploads/';
$config['allowed_types'] = 'gif|jpg|png';
$config['max_size']    = '100';
$config['max_width'] = '1024';
$config['max_height'] = '768';
}

#auto -load
$autoload['libraries'] = array('database','form_validation','session','user_agent', 'pagination', 'My_PHPMailer', 'upload'); 


Am using code igniter 3
error is like...

Code:

An uncaught Exception was encountered
Message: syntax error, unexpected '$config' (T_VARIABLE), expecting function (T_FUNCTION) or const (T_CONST)

libraries/upload.php

Line Number: 5

can you please help me to solve this