PHP SPL 标准库之 Countable

Countable {
/* 方法 */
abstract public count ( void ) : int
}

class MyCount 
{
 private $num;

 public function __construct($num) 
 {
 $this->num = $num;
 }

 public function count() 
 {
 return $this->num;
 }
}

$obj = new MyCount(10);

echo count($obj);//返回1

class MyCount implements \Countable
{
 private $num;

 public function __construct($num) 
 {
 $this->num = $num;
 }

 public function count() 
 {
 return $this->num;
 }
}

$obj = new MyCount(10);

echo count($obj);//返回10