从类中访问全局变量 [英] Access global variable from within a class

问题描述

我有以下(简化的)代码:

I have the following (stripped down) code:

<?PHP
    class A {
        function Show(){
            echo "ciao";
        }
    }

    $a = new A();
    $b = new B();

    class B {
        function __construct() {
            $a->Show();
        }
    }
?>

有点意外，我无法从类内部访问全局定义的$ a变量，并且出现了 Undefined variable 异常.有帮助吗?

With a bit of surprise I cannot access the globally defined $a variable from within the class and I get a Undefined variable exception. Any help?

推荐答案

为什么会感到惊讶?那是一个相当合理的变量范围问题...

Why the surprise? That's a pretty logical variable scope problem there...

我建议您使用global关键字或变量$GLOBALS来访问变量.

I suggest you use either the global keyword or the variable $GLOBALS to access your variable.

编辑:因此，在您的情况下，将是:

So, in your case that will be:

global $a;
$a->Show();

或

$GLOBALS['a']->Show();

而且，由于Vinko是正确的，我建议您阅读有关

EDIT 2: And, since Vinko is right, I suggest you take a look at PHP's manual about variable scope.

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