public function request_dropbox()
{
    $params['key'] = 'gr3kempuvsiqsli';
    $params['secret'] = 'qtdl8lmm9r0rlk1';
    $this->load->library('dropbox', $params); 
    $data = $this->dropbox->get_request_token(base_url());
    $this->session->set_userdata('token_secret', $data['token_secret']);
    redirect($data['redirect']);
}
//This method should not be called directly, it will be called after 
//the user approves your application and dropbox redirects to it
public function access_dropbox()
{
    $params['key'] = 'gr3kempuvsiqsli';
    $params['secret'] = 'qtdl8lmm9r0rlk1';
    $this->load->library('dropbox', $params);
    $oauth = $this->dropbox->get_access_token($this->session->userdata('token_secret'));        
    $this->session->set_userdata('oauth_token', $oauth['oauth_token']);
    $this->session->set_userdata('oauth_token_secret', $oauth['oauth_token_secret']);
    redirect('welcome/test_dropbox');
}
//Once your application is approved you can proceed to load the library
//with the access token data stored in the session. If you see your account
//information printed out then you have successfully authenticated with
//dropbox and can use the library to interact with your account.
public function test_dropbox()
{
    $params['key'] = 'gr3kempuvsiqsli';
    $params['secret'] = 'qtdl8lmm9r0rlk1';
    $params['access'] = array('oauth_token'=>urlencode($this->session->userdata('oauth_token')),
                              'oauth_token_secret'=>urlencode($this->session->userdata('oauth_token_secret')));
    $this->load->library('dropbox', $params);
    $dbobj = $this->dropbox->account();
    print_r($dbobj);
}
Blockquote i have used Dropbox library https://github.com/jimdoescode/CodeIgniter-Dropbox-API-Library When i call to function request_dropbox() it gives me error in api "Fatal error: Call to undefined function curl_init() in C:\xampp\htdocs\reports\application\libraries\Dropbox.php on line 478" please help me how to access dropbox files.