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class BenHang extends Card{ /*构造函数与及构造的继承*/ function __construct($cardno,$pwd, $name,$money){ parent::__construct($cardno,$pwd, $name,$money); } function take($money){ echo "本行取款{$money}没有手续费·····<br>"; }function zhuan($money){ echo "本行转账{$money}·····<br>"; } }$benhang=new BenHang(123,344,444,444);$benhang->check();$benhang->take(234);$benhang->zhuan(4555);/*其他银行卡的类*/class Qita extends Card{function __construct($cardno,$pwd, $name,$money){ parent::__construct($cardno,$pwd, $name,$money); } function take($money){ echo "非本行取款{$money}有手续费2元·····<br>"; } }$qita=new Qita(123,344,444,444);$qita->check();$qita->take(99);
PHP's three major characteristics: inheritance, packaging, polymorphism
1. How to implement inheritance?
Use the extends keyword for the subclass to inherit the parent class;
class Student extends Person{}# 2. Things to note when implementing inheritance?
① Subclasses can only inherit non-private properties of the parent class.
②After a subclass inherits a parent class, it is equivalent to copying the properties and methods of the parent class to the subclass, which can be called directly using $this.
③ PHP can only support single inheritance and does not support one class inheriting multiple classes. But a class carries out multi-level inheritance;
class Student extends Chengnian{}
//Student class has both Chengnian class and Person class Properties and methods
3. Method override (method rewriting)## Condition ① Subclass Inherit from parent class.
Condition ② The subclass overrides the existing method of the parent class.
Meeting the above two conditions is called method coverage. After overriding, when a subclass calls a method, the subclass's own method will be called. Similarly, in addition to method overrides, subclasses can also have attributes with the same name as the parent class for attribute overrides.
4. If the subclass overrides the parent class method, how to call the parent class method with the same name in the subclass?
partent::method name();
Therefore, when a subclass inherits a parent class, it needs to be The first step in the construction is to call the parent class constructor to copy.
function __construct($name,$sex,$school){
parent::__construct($name,$sex);
$this->school = $school;
}
实例一枚:
class Person{protected $name;public $sex; function __construct($name,$sex){ //声明构造函数 $this->name = $name; $this->sex = $sex; } function say(){ echo "我叫{$this->name},我是{$this->sex}生!<br>"; } } class Student extends Person{ //子类继承父类public $school; function __construct($name,$sex,$school){ //子类的构造函数 parent::__construct($name,$sex); //调用父类构造进行复制$this->school = $school; } function program(){ echo "PHP真好玩!我爱PHP!PHP是世界上最好用的编程语言!<br>"; } function say(){ parent::say(); //重写父类的同名方法echo "我是{$this->school}的"; } } $zhangsan = new Student("张三","男","起航"); $zhangsan->say(); $zhangsan->program();
二、封装
class Person{public $name;public $age;public $sex; function __construct($name, $age,$sex){ $this->name=$name; $this->setAge($age); $this->setSex($sex); } function setAge($age){if($age>=0&&$age<=120){return $this->age=$age; }else{ die("年龄输入有误!!!"); } } function setSex($sex){if($sex=="女"||$sex=="男"){return $this->sex=$sex; }else{ die("性别输入有误!!!"); } } function say(){ echo "我的名字叫{$this->name},我的年龄{$this->age},我的性别是{$this->sex}<br>"; } }class Work extends Person{private $position; function __construct($name, $age,$sex,$position){ parent::__construct($name, $age,$sex); $this->job=$job; $this->setPosition($position); } function setPosition($position){ $arr=['总监','董事长','程序员','清洁工'];if(in_array($position, $arr)){return $this->position=$position; }else{ die("不存在该职位"); } } function __set($key,$value){if($key=="age"){return parent::setAge($value); } elseif($key=="sex"){return parent::setSex($value); } elseif($key=="position"){return $this->setPosition($value); }return $this->$key=$value; } function say(){ parent::say(); echo "我的职位是{$this->position}"; } } $zhangsan=new Work("张三",22,"男","总监"); $zhangsan->setSex("女"); $zhangsan->setAge(30);// $zhangsan->setPosition("董事长");$zhangsan->position="董事长"; $zhangsan->name="lisi";$zhangsan->say();
/*墨盒接口 * 纸张接口*/ interface InkBox{ function color(); }interface Paper{ function sizes(); }class Computer{function fangfa(InkBox $a,Paper $b){ //父类引用echo "即将开始打印····<br>"; $a->color();$b->sizes();echo "打印结束···<br>"; } }class Color implements InkBox{function color(){echo "正在装载彩色墨盒<br>";echo "实现彩色墨盒<br>"; } }class White implements InkBox{function color(){echo "正在装载黑白墨盒<br>"; echo "实现黑白墨盒<br>"; } }class A4 implements Paper{function sizes(){echo "正在加载A4纸张<br>";echo "实现A4纸张<br>"; } }class A5 implements Paper{function sizes(){echo "实现A5纸张<br>"; } }$com=new Computer();//创建对象$com->fangfa(new Color(),new A4());//子类对象
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