php版本是7.2,出现了如下错误

Use of undefined constant XXXXXXX - assumed 'XXXXX' (this will throw an Error in a future version of PHP) 

网上查了些，可能要将PHP版本降成5.6，或者装多个版本PHP切换也可以，

Warning: Use of undefined constant datelist - assumed 'datelist' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\stbc\apply.php on line 6

 PHP第六行很简单 就是：$datelist=$_POST[datelist];