在 python 函数分配中遇到问题

Question

我正在从codecademy做Python，并且在计划假期作业(7/7(中遇到麻烦。

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下给出输入时，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

raw_input返回一个字符串，你不能用字符串做数学运算。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?'))

Answer 2

这里有一些问题，但首先，如果你的作业允许，我会使用一个类而不是多个函数。我只会创建 1 个大对象。原因是您有太多的参数，因此将参数传递给类然后允许函数操作它们而不是将参数传递给多个函数更有意义。一切都很相似，因为它都与旅行有关，所以我会把它存储在一个类中。我使用的是 Python 3.6，因此这与您使用的 Python 2 版本略有不同，但如您所见，我仍然必须将用户输入转换为整数值。在代码中，您不会将用户输入转换为整数值，而是尝试对数据执行数学运算。这也应该给你一个回溯。您必须在raw_input之前实际定义数据类型。输入函数在 Python 2 中不会像在 Python 3.6 中那样工作。但是如果你曾经用Java编码过，它本质上就像声明一个变量。此外，当在这里获取用户输入时，我会更改城市以使用 .lower(( 方法评估值是多少。信任大写的用户是有风险的。我在这里做了一些其他更改，希望它有所帮助。

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())

这是您的输出：

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