PHP this,self 跟 parent 关键字

<?phpclass 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 ?>