How to do Pagination in CodeIgniter

Controller.php

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

class Country extends CI_Controller {

    public function __construct()
    {
        parent:: __construct();
        $this->load->model('Country_model', 'country');
        $this->load->library("pagination");
    }
    public function listing()
    {
        $config = array();
        $config["base_url"] = base_url() . "country/listing";
        $config["total_rows"] = $this->country->total_rows();
        $config["per_page"] = 20;
        $config["uri_segment"] = 3;

        $this->pagination->initialize($config);

        $page = ($this->uri->segment(3)) ? $this->uri->segment(3) : 0;
        $data["countries"] = $this->country->get_countries($config["per_page"], $page);
        $data["links"] = $this->pagination->create_links();

        $this->load->view("listing", $data);
    }
}