相关疑难解决方法(0)

我是OOP范例的新手,所以对这个问题可能有一个简单的解释......

您是否总是需要在类中声明公共对象范围的变量？例如:

<?php

class TestClass
{
    var $declaredVar;

    function __construct()
    {
        $this->declaredVar = "I am a declared variable.";
        $this->undeclaredVar = "I wasn't declared, but I still work.";
    }

    function display()
    {
        echo $this->declaredVar . "<br />";
        echo $this->undeclaredVar;
        echo "<br /><br />"; 
    }
}

$test = new TestClass;
$test->display();

$test->declaredVar = "The declared variable was changed.";
$test->undeclaredVar = "The undeclared variable was changed.";

$test->display();

?>

在这段代码中,即使$declaredVar是唯一声明的变量,$undeclaredVar也是可访问和可用的 - 它似乎就好像我已将其声明为public.

如果未声明的类变量总是可以像这样访问,那么预先声明它们的重点是什么？