Add more function in codeigniter form validation library

add library of MY_Form_validation and add function that you want to add in form validation library

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class MY_Form_validation extends CI_Form_validation {
    function __construct(){        parent::__construct();    }
    function error_array(){        return $this->_error_array;    }

}

and call function in your controller

if($this->form_validation->run()){
}else{
$this->form_validation->error_array();
}


error_array will return all the required parameter that you will getfrom 
form_error('field_name')