这三个词在定义类的属性和方法时使用,其最大的区别在与他们作用域不同
public :全局使用,不仅是本类,其子类,创建的对象都可以使用,甚至子类的子类由于继承关系,也可以使用.
protected:本类和其子类使用,如果后续有继承的话,
private : 仅限本类使用
???class ClassA ???{ ???????public $a = 1; ???????protected $b = 2; ???????private $c = 3; ???????public function share() { ???????????echo ‘a=‘.$this->a."\n"; ???????????echo ‘b=‘.$this->b."\n"; ???????????echo ‘c=‘.$this->c."\n"; ???????} ???????protected function fuZi() { ???????????echo ‘a=‘.$this->a."\n"; ???????????echo ‘b=‘.$this->b."\n"; ???????????echo ‘c=‘.$this->c."\n"; ???????} ???} ???class ClassB extends ClassA ???{ ???????public function ?jiCheng() { ?????????echo ?‘我是B类继承了protected的属性b=‘.$this->b."\n"; ?????????echo ?‘我是B类继承的protected方法‘.parent::fuZi()."\n"; ???????} ???????// ???????/*protected function fuzi() ???????{ ???????????echo ‘i am b‘; ???????}*/ ???} ???class ClassC extends ClassB ???{ ???????public function Cji() { ???????????echo ‘我是C类继承了B类a=‘.$this->a."\n"; ???????????echo ‘我是C类继承了B类b=‘.$this->b."\n"; ???????????$this->fuZi(); ???????????} ???} ???$classB = new ClassB(); ???$classB->jiCheng();//经过测试继承的protected方法属性都可以获取 ???$classC = new ClassC(); ???$classC->Cji();执行结果如下图
由于B继承了A,C又继承了B,因此就将A里protected属性和方法传递到了C,如果在B里面使用函数的覆盖,会发现C类里的fuZi函数也跟着变化,这说明protected属性的作用域是本类和子类,如果在子类中进行了覆盖,后续使用将是新的函数,将代码中B类fuZi函数注释释放,得到下图结果:
php 定义类属性和方法的public ?protected private 修饰词的区别
原文地址：https://www.cnblogs.com/MrBear/p/9988515.html