对类成员的访问控制
类成员都必须使用关键字public、protected 或 private 进行定义
声明类成员
<?php注意:
/** Define MyClass */
class MyClass
{ public $public = ’Public’;
protected $protected = ’Protected’;
private $private = ’Private’;
function printHello()
{ echo $this->public;
echo $this->protected;
echo $this->private;
}
}
$obj = new MyClass();
echo $obj->public; // // Works
echo $obj->protected; // Fatal Error
echo $obj->private; // Fatal Error
$obj->printHello();// Shows Public, Protected and Priv
class MyClass2 extends MyClass //Define MyClass2
{// We can redeclare the public and protected method, but not private
protected $protected = ’Protected2’;
function printHello()
{ echo $this->public;
echo $this->protected;
echo $this->private;
}
}
$obj2 = new MyClass2();
echo $obj->public; // Works
echo $obj2->private; // Undefined
echo $obj2->protected; // Fatal Error
$obj2->printHello();// Shows Public, Protected2, not Private
?>
在 PHP 4 中使用 var 关键字对变量进行定义的方法在 PHP 5 的面向对象语法中不再使用。为了顾及兼容性，在类中定义一个变量的话，该变量会被自动设为 public，并且产生一个 E_STRICT 警告。
