尝试这样的注销功能

function logout(){

function logout() {

   session_start();
   session_destroy();

}

1. 调用注销函数时，它不会调用session_start()，因此无法获取会话变量.应在编辑之前先获取它.

1. When you call the logout function,it doesn't call the session_start(),so you can't get the the session variables.You should get it before you will edit it.

详细信息: php.net session_destory()