PHP static variable usage, PHP static variable access method

class Child{
public $name;
//Define and initialize a static variable $nums Reference link: php static variable initialization
public static $nums =0;
function __construct($name){
$this->name=$name;
}
public function join_game(){< ;/p>
//self::$nums Use static variables
self::$nums+=1;
echo $this->name."Join making a snowman Game";
}
}
//Create three children
$child1=new Child("李逵");
$child1->join_game();
$child2=new Child("Zhang Fei");
$child2->join_game();
$child3=new Child("Tang Monk");
$child3->join_game();
 //Look how many people play the game
echo " There is this".Child::$nums;