理解self，this，parent

1 <?php
2
3 class UserName
4 { 
5     //定义成员属性 
6     private $name;
7 
8     //定义构造函数
9     function __construct( $name )
10     {
11          $this->name = $name; //这里已经使用了this指针
12     }
13 
14     //析构函数
15     function __destruct(){}
16
17     //打印用户名成员函数
18     function printName()
19     {
20          print( $this->name ); //又使用了this指针
21     }
22 }
23
24 //实例化对象
25 $nameObject = new UserName( "heiyeluren" );
26
27 //执行打印
28 $nameObject->printName(); //输出: heiyeluren
29
30 //第二次实例化对象
31 $nameObject2 = new UserName( "PHP5" );
32
33 //执行打印
34 $nameObject2->printName(); //输出：PHP5
35 ?>

1 <?php
2
3     class Counter
4     {
5         //定义属性，包括一个静态变量
6         private static $firstCount = 0;
7         private $lastCount;
8
9         //构造函数
10         function __construct()
11         {
12              $this->lastCount = ++selft::$firstCount; //使用self来调用静态变量,使用self调用必须使用::(域运算符号)
13         }
14
15         //打印最次数值
16         function printLastCount()
17         {
18              print( $this->lastCount );
19         } 
20     }
21
22 //实例化对象
23 $countObject = new Counter();
24
25 $countObject->printLastCount(); //输出 1
26
27 ?>

1 <?php
2
3 //基类
4 class Animal
5 {
6     //基类的属性
7     public $name; //名字
8
9     //基类的构造函数
10     public function __construct( $name )
11     {
12          $this->name = $name;
13     }
14 }
15
16 //派生类
17 class Person extends Animal //Person类继承了Animal类
18 {
19     public $personSex; //性别
20     public $personAge; //年龄
21
22     //继承类的构造函数
23     function __construct( $personSex, $personAge )
24     {
25          parent::__construct( "heiyeluren" ); //使用parent调用了父类的构造函数
26          $this->personSex = $personSex;
27          $this->personAge = $personAge;
28     }
29
30     function printPerson()
31     {
32          print( $this->name. " is " .$this->personSex. ",this year " .$this->personAge );
33      }
34 }
35
36 //实例化Person对象
37 $personObject = new Person( "male", "21");
38
39 //执行打印
40 $personObject->printPerson(); //输出：heiyeluren is male,this year 21
41
42 ?>