PHP this,self 跟 parent 关键字

<?php
class UserName
{ 
    //定义属性    
     private $name;
 
     //定义构造函数
    function __construct( $name )
     {
          $this->name = $name; //这里已经使用了this指针
     }
 
     //析构函数
     function __destruct(){}
     //打印用户名成员函数
     function printName()
     {
          print( $this->name ); //又使用了this指针
     }
 }
 //实例化对象
 $nameObject = new UserName( "heiyeluren" );
 //执行打印
 $nameObject->printName(); //输出: heiyeluren
 
 //第二次实例化对象
  $nameObject2 = new UserName( "PHP5" );
 
 //执行打印
 $nameObject2->printName(); //输出：PHP5
?>

<?php

     class Counter
     {
         //定义属性，包括一个静态变量
         private static $firstCount = 0;
         private $lastCount;
        //构造函数
         function __construct()
         {
              $this->lastCount = ++selft::$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)
         }
         //打印最次数值
        function printLastCount()
         {
              print( $this->lastCount );
         } 
    }

 //实例化对象
$countObject = new Counter();
$countObject->printLastCount(); //输出 1
?>

<?php
//基类
class Animal
{
    //基类的属性
     public $name; //名字
    //基类的构造函数
    public function __construct( $name )
     {
         $this->name = $name;
     }
}
 //派生类
 class Person extends Animal //Person类继承了Animal类
 {
    public $personSex; //性别
    public $personAge; //年龄
     //继承类的构造函数
     function __construct( $personSex, $personAge )
    {
          parent::__construct( "heiyeluren" ); //使用parent调用了父类的构造函数
          $this->personSex = $personSex;
         $this->personAge = $personAge;
    }
     function printPerson()
     {
          print( $this->name. " is " .$this->personSex. ",this year " .$this->personAge );
      }
 }
 //实例化Person对象
 $personObject = new Person( "male", "21");

 //执行打印
 $personObject->printPerson(); //输出：heiyeluren is male,this year 21

 ?>