ThinkPHP实现登录退出功能

public function login(){
if(!IS_POST){
$this->display();
}else{
//若验证码验证通过
if($this->checkyzm(I('post.yzm'))){
$username=I('post.username');
$user=D( ' user ' )->where(" username='$username' ")->find();
//post过来的password拼接盐md5后密码=数据库的密码，则通过
if(md5( I( ' post.password ' ) . $user[ ' salt ' ])===$user['password']{
cookie('username',$userp[ ' username ' ]);//写入cookie
$this->redirect('/');//跳转到首页
}else{
echo '用户名或密码不对';
}
}
}
}

/**V层

• 退出登陆
• 读取cookie $Think.cookie
  */
  //若没有cookie数据
  您好欢迎观临
  <if condition="$Think.cookie.username eq null">
  <a href="{:U('Home/User/login')}" rel="external nofollow" rel="external nofollow" style="color:#50884b">登陆 |
  <a href="{:U('Home/User/reg')}" rel="external nofollow" style="color:#50884b">免费注册 | {$Think.cookie.username}| <

/**

• 退出方法
• 1，cookie设为null，删除cookie
• 2. 跳转到首页
     */
     public function logout(){
     cookie('username',null);
     $this->redirect('/');
     }

?>}