Listing 6.7 Static members

class Counter
{
　private static $count = 0;
　const VERSION = 2.0;

　function __construct()
　{
　　self::$count++;
　}

　function __destruct()
　{
　　self::$count--;
　}

　static function getCount()
　{
　　return self::$count;
　}
};

//创建一个实例，则__construct()将执行
$c = new Counter();

//输出 1
print(Counter::getCount() . "n");

//输出类的版本属性
print("Version used: " . Counter::VERSION . "n");
?＞