ci-humanfilter
This CodeIgniter's Library is used to get a new paired question and answer from a list (you can modify this questions in the library) so the system can verify that the user that is sending any form is a human and not a bot.
Its usage is recommended for CodeIgniter 2 or greater.
$this->load->library('HumanFilter');
$this->humanfilter->get_new_question();
$question = $this->humanfilter->get_question();
$_SESSION['answer'] = $this->humanfilter->get_answer();