python做停车场计费系统代码

好的，下面是一个简单的Python停车场计费系统代码：

import datetime

class ParkingLot:
    def __init__(self):
        self.spaces = {}

    def park(self, car_number):
        if car_number not in self.spaces:
            self.spaces[car_number] = datetime.datetime.now()
            print(f"Car {car_number} parked at {self.spaces[car_number]}.")
        else:
            print(f"Car {car_number} is already parked.")

    def unpark(self, car_number):
        if car_number in self.spaces:
            time_elapsed = datetime.datetime.now() - self.spaces[car_number]
            hours_elapsed = time_elapsed.total_seconds() / 3600
            cost = round(hours_elapsed * 5, 2)
            del self.spaces[car_number]
            print(f"Car {car_number} unparked. Total cost: ${cost}.")
        else:
            print(f"Car {car_number} is not parked here.")

parking_lot = ParkingLot()
parking_lot.park("ABC123")
parking_lot.park("DEF456")
parking_lot.unpark("ABC123")
parking_lot.unpark("GHI789")

这个代码使用了Python的datetime模块来计算停车时间和费用。停车场对象ParkingLot有一个spaces字典，用来存储每个车辆的停车时间。当一个车辆进入停车场时，它的车牌号被添加到spaces中，并且打印出停车时间。当一个车辆离开停车场时，它的车牌号从spaces中删除，并且计算出停车时间和费用。费用按每小时5美元计算。如果一个车辆没有在停车场，输出一条错误信息。