Before running programm in your system set codeigniter base url properly?
How to set proper codeigniter base url?
$config['base_url'] = "http://somesite.com/somedir/";
If using the URL helper, then base_url() will output the above string.
Passing arguments to base_url() or site_url() will result in the following (assuming
$config['index_page'] = "index.php";:
echo base_url('assets/stylesheet.css'); //http://somesite.com/somedir/assets/stylesheet.css
echo site_url('mycontroller/mymethod'); //http://somesite.com/somedir/index.php/mycontroller/mymethod