class db

{

  function __construct()
  {           
     
   $this->mConnId=mysql_connect ($this->DbHost,$this->DbUser,$this->DbPwd);//建立連接

            mysql_select_db($this->DbName, $this->mConnId);    //選擇數據庫

            mysql_query("set names 'gbk'");//設置數據庫編碼為GBK

        }
       
        //__destruct：析構函數，斷開連接

 function __destruct()
  {
            mysql_close($this->mConnId); //此處還有問題......

        }
 }

// 這時我們在用時就不需要考慮數據連接與關閉了，只要$aa = new db();就OK了。
 

 <?php
    class Car{
        private $color;
        private $size;
        private $price;
        function __construct(){
            $this->color="red";
            $this->size=4;
            $this->price=30000;
        }

        public function display(){
            echo $this->color."<br>";
            echo $this->size."<br>";
            echo $this->price."<br>";
        }
    }
    $car=new Car();
    $car->display();
?>