接口
- Countable::count()
- 统计一个对象的元素个数
- OuterIterator::getInnerIterator()
- Returnstheinneriteratorforthecurrententry
- RecursiveIterator::getChildren()
- Returnsaniteratorforthecurrententry
- RecursiveIterator::hasChildren()
- Returnsifaniteratorcanbecreatedforthecurrententry
- SeekableIterator::seek()
- Seekstoaposition
- SplObserver::update()
- Receiveupdatefromsubject
- SplSubject::attach()
- AttachanSplObserver
- SplSubject::detach()
- Detachanobserver
- SplSubject::notify()
- Notifyanobserver