追溯（最近一次呼叫過去）：和TypeError：

Question

我仍然是Python的初學者，目前正在使用codecademy。 我決定稍微簡化其中一個練習程序，但遇到了這個錯誤：

Traceback (most recent call last):
File "python", line 30, in <module>
File "python", line 24, in trip_cost
File "python", line 18, in rental_car_cost
TypeError: unsupported operand type(s) for -: 'unicode' and 'int'

這是我的代碼：

def hotel_cost(nights):
  # the hotel costs $140 per night
  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

x = raw_input("Where are you going? ")
y = raw_input("How many days are you going for? ")
z = raw_input("How much spending money are you taking? ")

print trip_cost(x, y, z)

任何幫助將不勝感激，謝謝！ 我是一個初學者，所以我的python術語有點生銹。

Answer 1

您正在做days - 1或cost -= 50但是days和cost是用戶輸入，因此是一個字符串（在您的情況下，unicode字符串更准確），您應該在執行任何操作（尤其是數學運算）之前將其轉換為int ，因為這是您的意圖：

y = int(raw_input("How many days are you going for? "))
z = int(raw_input("How much spending money are you taking? "))

這是因為您將它們當作數字使用，而沒有轉換

但是請注意，輸入數字以外的任何數字都會產生錯誤，但這是另一個問題的主題