说明：  PHP初学者头疼问题总结：页面之间无法传递变量 get,post,session在最新的php版本中自动全局变量是关闭的，所以要从上一页面取得提交过来得变量要使用$_GET[ foo ],$_POST[ foo ],$_SESSION[ foo ]来得到
(PHP beginners headaches conclusion : pages are unable to pass variables get, post, session in the latest php version of global variables is automatically closed. Therefore, we should proceed from the field Previous submit them to be used in the variable $ _GET [foo] $ _POST [foo], $ _SESSION [foo] to be)