请记住，我的代码在我的脚本php中不起作用

我的脚本中有3页1.header.php2.auth.php3.主页.php

头文件有登录代码，函数和数据库连接在auth.php中。

现在登录正在工作，唯一的就是cookie，我的意思是我想知道如何在脚本中添加记住功能，请帮忙。这是我的代码1.header.php

include 'auth.php';
if(empty($_POST['submitlogin']) === false)
{
$username = $_POST['username'];
$password = $_POST['password'];  
if(empty($username) === true)
  {
      $errors[] = '<font color="#FFFFFF">You need to enter an username!</font>';
  } 
 if(empty($password) === true)
  {
      $errors[] = '<font color="#FFFFFF">You need to enter password!</font>';
  } 
else if(user_exists($username) === false )
  {
      if(empty($username) === true){}
      else
        $errors[] = '<font color="#FFFFFF">No such username has been found.</font>';
  } 
else if(user_active($username) === false)
  {
      $errors[] = '<font color="#FFFFFF">You haven''t activated your account.</font>';
  }
else
  {
    $login = login($username, $password);
    if($login === false)
    {
        $errors[] = '<font color="#FFFFFF">The Username/Password Combination is incorrect</font>';
    } 
    else 
    {
        $_SESSION['user_id'] = $login;
        header('Location: home.php');
        exit();
    }
  }
}

2.auth.php代码

session_start();
error_reporting(0);
require 'connect.php';

if(logged_in() === true){
  $session_user_id = $_SESSION['user_id'];
  $user_data = user_data($session_user_id, 'user_id', 'username', 'password',  'email', 'active', 'type');

  if(user_active($user_data['username']) === false)
    {
      session_destroy(); 
      header('Location: home.php');
      exit();
    }
        }else{
       }
    $errors = array();

  function user_data($user_id)
   {
  $data = array();
  $user_id = (int)$user_id;
  $func_num_args = func_num_args();
  $func_get_args = func_get_args();
  if($func_num_args > 1)
  {
     unset($func_get_args[0]); 
     $fields = '`' . implode('`, `', $func_get_args) . '`';
     $data = mysql_fetch_assoc(mysql_query("SELECT $fields FROM `edge_users` WHERE `user_id` = $user_id"));
     return $data;
  }
   }

   function user_active($username) 
   {
    $username = sanitize($username);
    return (mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `edge_users` WHERE  `username` = '$username' AND `active` = 1"), 0)==1)?true: false;  }

    function login($username, $password)
     {
  $user_id = user_id_from_username($username);
  $username = sanitize($username);
  $password = md5($password);
  return (mysql_result(mysql_query("SELECT COUNT(`user_id`) FROM `edge_users` WHERE  `username` = '$username' AND `password` = '$password'"), 0)  == 1) ? $user_id : false;
      }

Html表单

  <form  method="post">
  Username
   <input type="text" name="username" style="padding: 5px; width:228px; height:15px;"  autocomplete="off" value="<?php echo $_POST['username'];?>"/>>         
   Password
   <input type="password" name="password" style="padding: 5px;  width:228px;height:15px;" />                                                                    
   <input type="checkbox" name="rememberme" /> Remember Me  
   <input type="submit" name="submitlogin"  style="background: #00c800; border:1px  solid  #00c800; color:#FFFFFF; padding:5px 10px 5px 10px; font-size:14px; float: right;"  value="Login" />
    </form>