Question

def hotelcost(nights):
    cost = 140
    return nights * cost

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

def rentalcarcost(days):
    cost = 40 * days
    if days >= 7:
        cost - 50
    elif days >= 3:
        cost - 20
    else:
        return cost
def tripcost(city,days,spendingmoney):
    return planeridecost(city) + hotelcost(days) + rentalcarcost(days) + spendingmoney
    print tripcost
    return tripcost

tripcost("Los Angeles",5,600)

我无法用Python解决这个问题。我已经尝试了其他几个代码来执行相同的操作，但我无法执行：

Traceback (most recent call last):
  File "python", line 28, in <module>:
  File "python", line 25, in tripcost:
TypeError: unsupported operand type(s) for +: 'int' and 'NoneType'

Answer 1

您的rentalcarcost()函数仅返回其中一个分支中的cost值：

def rentalcarcost(days):
    cost = 40 * days
    if days >= 7:
        cost - 50
    elif days >= 3:
        cost - 20
    else:
        return cost

因此，只有当days超过3时才会返回成本。其他分支也需要包含return语句，否则您最终会返回None：

def rentalcarcost(days):
    cost = 40 * days
    if days >= 7:
        return cost - 50
    elif days >= 3:
        return cost - 20
    else:
        return cost

Answer 2

对于天> gt = = 7且天＆gt; = 3的情况，Rentalcarcost函数返回None。如下所示：

def rentalcarcost(days):
    cost = 40 * days
    if days >= 7:
        return (cost - 50)
    elif days >= 3:
        return (cost - 20)
    else:
        return cost

你的tripcost功能有2个返回，第二个没用。

无法计算tripcost，而是抱怨NoneType

2 个答案: