$this->form_validation->set_rules('licoef', 'coef', 'integer'|'exact_length[1]');
// So instead of 'integer'|'exact_length[1]' // try 'integer|exact_length[1]'
$this->form_validation->set_rules('licoef', 'coef', 'integer|exact_length[1]');
function _validate_liceof($str="") { $str = (int)$str; if ($str < 5 || $str > 15) { $this->form_validation->set_message('_validate_liceof', 'You must enter a number between 5 and 15'); return FALSE; } return TRUE; }