PHP 객체지향 구문 5 최종 클래스, 추상 클래스, 인터페이스 구조(클래스 아님)

final class End{
}
class Test  extends End{
}

运行结果：报错
PHP Fatal error: Class Test may not inherit from final class (End) in /usercode/file.php on line 7

<?php
class  AmParent{
    final public function end_func(){
        echo &#39;我是final方法&#39;;
    }
}
class AmChild extends AmParent{
     public function end_func(){
        echo &#39;我是子类，我想重写final方法，可是报错了&#39;;
    }
}

运行结果：报错
PHP Fatal error: Cannot override final method AmParentt::end_func() in /usercode/file.php on line 11

abstract public function abstract_func($arg1,$arg2)

//不能实例化对象
<?php
abstract class AmParent{
    abstract public function abstract_func($arg1,$arg2);
}
$amParent=new AmParent;

运行结果：
PHP Fatal error: Cannot instantiate abstract class AmParent in /usercode/file.php on line 5

<?php
abstract class AmParent{
    abstract public function abstract_func($arg1,$arg2);
}
class AmChild extends AmParent{
}

运行结果，报错：
PHP Fatal error: Class AmChild contains 1 abstract method and must therefore be 
declared abstract or implement the remaining methods (AmParent::abstract_func) in /usercode/file.php on line 6

<?php
abstract class AmParent{
    abstract public function abstract_func($arg1,$arg2);
}
abstract class AmChild extends AmParent{
}

<?php
abstract class AmParent{
    abstract public function abstract_func($arg1,$arg2);
}
 class AmChild extends AmParent{
     public function abstract_func($arg1,$arg2){
        echo $arg1.$arg2;
         }
}
$amChild=new AmChild;
$amChild->abstract_func( &#39;have implemented &#39;,&#39; abstract_func &#39;);

运行结果，报错：
have implemented abstract_func

<?php
abstract class Goods{
    abstract public function sayName();
}
 class Books extends  Goods{
     public function sayName(){
         echo &#39;我是一本书的名字<br/>&#39;;
     }
}
 class Mobiles extends  Goods{
     public function sayName(){
         echo &#39;我是一部手机的名字<br/>&#39;;
     }
}
$book1=new Books;
$book1->sayName();
$mobile1=new Mobiles;
$mobile1->sayName();

运行结果：
我是一本书的名字
我是一部手机的名字

<?php
    interface iGoods{
        const PAI=3.14;
        public function sayName();
        public function sayPrice();
    }

//1定义成抽象类
abstract class Books implements iGoods{
    abstract  public function sayName();
    abstract  public function sayPrice();
}

//2实现接口方法
 class Books implements iGoods{
     public function sayName(){
         echo '我实现了接口方法';
     }
     public function sayPrice(){
         echo '我实现了接口方法';
     }
}

<?php
interface iA{
        const PAI=3.14;
    public function sayA();
}
interface iB{
    public function sayB();
}
class C implements iA,iB{
    public function sayA(){
    }
    public function sayB(){
    }
}

//用class_exists（@param string），判断类是否存在
var_dump(class_exists('C'));
var_dump(class_exists('iA'));

运行结果：
bool(true)
bool(false)