Online PHP editor | output for aWqn0

<?php class A { protected static $member_counter = 0; public static function counter() { static $counter = 0; $counter++; return $counter; } public static function member_counter(){ static::$member_counter++; return static::$member_counter; } } class B extends A { protected static $member_counter = 0; } var_dump(A::counter()); // int(1) var_dump(A::counter()); // int(2) var_dump(B::counter()); // int(3), previously int(1) var_dump(B::counter()); // int(4), previously int(2) echo '======================='.PHP_EOL; var_dump(A::member_counter()); // int(1) var_dump(A::member_counter()); // int(2) var_dump(B::member_counter()); // int(1) var_dump(B::member_counter()); // int(2)