python函数有问题吗

Question

我正在做codecademy的Python，在计划假期作业时遇到了麻烦（7/7）。你知道吗

def hotel_cost(nights):
  return 140*nights

def plane_ride_cost(city):
  if city == 'Charlotte':
    return 183
  elif city == 'Tampa':
    return 220
  elif city == 'Pittsburgh':
    return 222
  elif city == 'Los Angeles':
    return 475

def rental_car_cost(days):
  cost = days*40
  if days >= 7:
    cost -= 50
  elif days >= 3 and days <7:
    cost -= 20
  return cost

def trip_cost(city,days,spending_money):
  return rental_car_cost(days)+hotel_cost(days - 1)+plane_ride_cost(city)+spending_money

city = raw_input('city?')
days = raw_input('days?')
spending_money = raw_input('money?')
print trip_cost(city,days,spending_money)

当我运行脚本并在提示符处输入时，它失败，并显示以下错误：

Traceback (most recent call last):
  File "python", line 28, in <module>
  File "python", line 23, in trip_cost
  File "python", line 17, in rental_car_cost
TypeError: unsupported operand type(s) for -=: 'unicode' and 'int'

Answer 1

这里有一些问题，但是首先，如果你的赋值允许，我会使用一个类而不是多个函数。我只需要创建一个大对象。原因是您有太多的参数，所以将参数传递给类，然后允许函数对其进行操作比将参数传递给多个函数更有意义。一切都是相似的，因为它都与旅行有关，所以我把它存储在一个类中。我使用的是Python3.6，因此它与您使用的Python2版本略有不同，但是您可以看到，我仍然需要将用户输入转换为整数值。在代码中，您不是将用户输入转换为整数值，而是尝试对数据执行数学运算。这也会给你一个回溯。您必须在原始输入之前定义数据类型。输入函数在Python2中的工作方式不会像在Python3.6中那样。但是，如果您曾经用Java编写过代码，它本质上就像声明一个变量。另外，在这里获取用户输入时，我会更改cities，以使用.lower（）方法计算值。信任用户是有风险的。我在这里做了一些其他的改变，希望能有所帮助。你知道吗

class BigTrip():

   def __init__(self, nights, days, city, spending_money):

      self.nights = nights
      self.days = days
      self.city = city
      self.spending_money = spending_money

   def hotel_cost(self):
      self.hotel_cost = 140 * self.nights
      return "Your hotel cost will be " + str(self.hotel_cost) + " dollars."

   def plane_ride_cost(self):

      if city.lower() == 'charlotte':
          self.plane_cost = 183
      elif city.lower() == 'tampa':
          self.plane_cost = 220
      elif city.lower() == 'pittsburgh':
          self.plane_cost = 222
      elif city.lower() == 'los angeles':
          self.plane_cost = 475
      return "Your plane cost will be " + str(self.plane_cost) + " dollars."

   def rental_car_cost(self):


      self.rental_cost = self.days * 40
      if int(self.days) >= 7:
          self.rental_cost -= 50
      elif int(self.days) >= 3 and int(self.days) <7:
          self.rental_cost -= 20
      return "Your rental car cost will be " + str(self.rental_cost) + " dollars."

   def trip_cost(self):
      return "Your total trip cost will be: {} dollars".format(self.days + self.hotel_cost + self.plane_cost + self.spending_money)


nights = int(input("How many nights will you stay in the city?: "))

city = input('\nSelect a city[Charlotte, Tampa, Pittsburgh or Los Angeles]: ')

days = int(input('How many days will you be staying?: '))

spending_money = int(input('How much spending money do you have?: '))

my_trip = BigTrip(nights, days, city, spending_money)
print(my_trip.hotel_cost())
print(my_trip.plane_ride_cost())
print(my_trip.rental_car_cost())
print(my_trip.trip_cost())

以下是您的输出：

How many nights will you stay in the city?: 4
Select a city[Charlotte, Tampa, Pittsburgh or Los Angeles]: charlotte
How many days will you be staying?: 3
How much spending money do you have?: 1200
Your hotel cost will be 560 dollars.
Your plane cost will be 183 dollars.
Your rental car cost will be 100 dollars.
Your total trip cost will be: 1946 dollars

Answer 2

raw_input返回一个字符串，不能用字符串进行数学运算。您需要将适当的值转换为数字，例如：

days = int(raw_input('days?'))
spending_money = float(raw_input('money?'))