Banking and Currency on Yangtze River Cruise Ship

Usually the cruise ships don't provide money-exchange service on board, so it's suggested to get some cash in hand for some small purchase during the shore excursions, like the souvenirs etc. What's more, any expense on the cruise ships. Like the room service, laundry, drinks at bar, internet, doctor visiting etc. are supposed to pay the end of each cruise with either credit card or cash (Some travelers checks are acceptable on board, some are not. So check with each individual ship before get on board).