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php继承中方法重载(覆盖)的应用场合,php重载
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php继承中方法重载(覆盖)的应用场合,php重载

Jun 13, 2016 am 09:15 AM
php Polymorphism method Overload

php继承中方法重载(覆盖)的应用场合,php重载

本文实例分析了php继承中方法重载(覆盖)的应用场合。分享给大家供大家参考。具体分析如下:

方法重载(override)/覆盖——在什么情况下使用:当父类知道所有的子类都需要用到一个方法,但父类不知道怎么去写这个方法时,就需要用到方法的重载。这时候,可以让子类去重写,来覆盖这个方法。

通俗实例——父类(动物)知道其子类(猫和狗)都会叫,但它们的叫法都不一样,所以父类没法去写这个方法,只能让子类(猫和狗)去定义。代码如下:

<&#63;php
class Animal{
 public $name;
 protected $price;
 
 function cry(){
 echo "不知道动物怎么叫";
 }
}
class Dog extends Animal{
 function cry(){
 echo "汪汪...";
 }
}
class Pig extends Animal{
 function cry(){
 echo "哼哼..."
 }
}
&#63;>

Copy after login

方法重载/覆盖的要点与细节(读起来有点呦口):

1、要求子类的方法,其方法名称、参数列表与父类方法一模一样。如例子中cry(),不能添加参数,改成cry($naaa)等。注意:这里并不要求参数名一样,只是要求参数的个数是一样的。
2、所谓的重载或覆盖,并不是将父类的方法覆盖。也可以这么理解:如果子类有调用该方法时,如果在自己类里找不到这个方法,那么它会去找父类里,看有没有这个方法。这也是多态的理解
3、如果子类里某个方法,要把父类里相同名称方法里的内容继承下来,可以使用 parent::方法名 或 父类名::方法名 继承。在子类定义的方法内使用。
4、访问权限问题,子类的访问范围>=父类的访问范围,即如果父类是protected function cry(),子类则只能是protected或public。

希望本文所述对大家的php程序设计有所帮助。

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