PHP工程师笔试题

//已经定义以下php类
class People{
    static $version = "1.02beta";
    private $age;
    
    public function m($key,$value=NULL){
        if($value == NULL){
            return $this->key;
        }else{
            $this->key = $value;
        }
    }
}
//1、用echo输出People的版本号
echo People::$version;

echo "<br/>";

//2、实例化一个People,叫$jack,并给他的age赋值为50
$jack = new People();
$jack->m("age",50);
echo $jack->m("age");
　　

/**
 * 继承People的子类Child,Child在实例化时,会自动echo父类的版本号。
 */

/**People.class.php文件**/
class People{
    static $version = "1.02beta";
    private $age;
    
    public function m($key,$value=NULL){
        if($value == NULL){
            return $this->key;
        }else{
            $this->key = $value;
        }
    }
}

/**Child.class.php文件**/
require "People.class.php";
class Child extends People{
	public function __construct(){
		echo parent::$version;//输出父类版本号
	}
}

//输出父类版本号
new Child();