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php可定义预定义变量吗？

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Jun 06, 2016 pm 08:43 PM

php

PHP已经有预定义全局变量

$_POST,$_GET,$_COOKIE,$_ENV,$SERVER

请问自己还在定义吗？

如果可以是不是必须要通过拓展来实现呢？

回复内容：

PHP已经有预定义全局变量

$_POST,$_GET,$_COOKIE,$_ENV,$SERVER

请问自己还在定义吗？

如果可以是不是必须要通过拓展来实现呢？

这些都是超全局变量，有了这些就足够你使用了。

你可以把你的变量按照作用域分为Global Scope, Session Scope, Page Scope, Request Scope等。然后分别可以保存到$_ENV,$_SESSION, $_POST,$_GET等。只要可以取到就好了。

还有一种办法就是定义常量。在其他文件里面包含。常量有很多的限制。

不行的。你不能够定义超全局的变量。常量定义之后可以不受作用域限制，但是一经定义不能修改。

应该可以在$GLOBALS里设置，不过不知道这样做有什么作用

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