How is it when i check out a hotel early, i must still pay the whole price?

Well, you still pay the whole price. When you check-in, you should present your passport. By Law visitors must present personal documents for hotel records. These documents will be returned upon departure. The check out time is please inform the reception if you wish to retain your room beyond this time. Extension will be given depending on the availability. If you just wanna leave the hotel room early (no more than one day), you still need to pay the whole price.

That is right. If you check in a room for overnight stay, whole price is needed to pay whenever you check out. You have another choice: choose the hourly stay like 4h or so according to your plan, which costs less than overnight stay.