如何修正这个“列表索引必须是整数或切片，而不是str”的TypeError？

Question

这是工作的代码：

candy_name = ["Assorted Small Lollipops", "Assorted Flavours Small", "Assorted Flavours Large", "Large Lollipop", "100g Assorted Flavours Small", "100g Assorted Flavours Large", "Candy Cane", "100g Candy Canes"]
candy_price = [0.1, 0.05, 0.2, 0.5, 4.5, 6, 0.2, 5.5]
candy_info = dict(zip(candy_name, candy_price))
candy_order, number_order, total = [], [], 0


while True:
    candy = input("which candy do you want?")

    while candy not in candy_info:
        candy = input("input error, try again:")
    candy_order.append(candy)
    number = input("How many %s would you like? " % candy)

    while not number.isdigit() or int(number) <= 0:
        number = input("Only integers greater than 0 are allowed, try again: ")
    number_order.append(int(number))

    keep_ordering = input("Would you like to add more to your order? y/n")
    while keep_ordering not in ["y", "n"]:
        keep_ordering = input("Simply enter y or n, try again:")

    if keep_ordering != "y":
        for _candy, _number in zip(candy_order, number_order):
            total += candy_info[_candy] * _number
        print("Your total spend is $%f" % total)
        break

但是，当我尝试在我自己的代码中实现它时，它不起作用，有人知道我做错了什么吗？我让它工作了几次，我不知道我是否改变了什么，使它不起作用

candy_name = ["Assorted Small Lollipops", "Assorted Flavours Small", "Assorted Flavours Large", "Large Lollipop", "100g Assorted Flavours Small", "100g Assorted Flavours Large", "Candy Cane", "100g Candy Canes"] #list with all candy types
candy_price = [0.1, 0.05, 0.2, 0.5, 4.5, 6, 0.2, 5.5] #all candy prices
total = 0
price_and_name = dict(zip(candy_name, candy_price))
candy_order = []
price_order = []
number_order = []

while True:
  for candies, price in zip(candy_name, candy_price):
    print(candies, "is $", price) #zips the two lists together so they line up

  price_and_name = [price_and_name.lower() for price_and_name in ["Assorted Small Lollipops", "Assorted Flavours Small", "Assorted Flavours Large", "Large Lollipop", "100g Assorted Flavours Small", "100g Assorted Flavours Large","Candy Cane", "100g Candy Canes"]] #makes the dictionary lowercase so the user input case doesn't matter
  
  candy = input("What candy would you like to order? ").lower()

  while candy not in price_and_name:
    candy = input("That was not one of the options, check your spelling and try again. ").lower()
  candy_order.append(candy)
  number = input("How many %s would you like? " % candy)

  while not number.isdigit() or int(number) <= 0:
    number = input("Only integers greater than 0 are allowed, please try again.")
  number_order.append(int(number))

  keep_ordering = input("Would you like to add more to your order? ").lower()
  while keep_ordering not in ["yes", "no"]:
    keep_ordering = input("Please enter just yes or no, try again. ").lower()

  if keep_ordering != "yes":
    for _candy, _number in zip(candy_order, number_order):
      total += price_and_name[_candy] + _number
    print("Your total is $%f" % total)
    break

以下是完整的错误消息：全错误信息

谢谢你的帮助。

Answer 1

得到该错误的原因是，price_and_name变量是一个列表，您可能认为它是一个字典。您最初创建的字典在这里被列表所取代：

price_and_name = [price_and_name.lower() for price_and_name in ["Assorted Small Lollipops", "Assorted Flavours Small", "Assorted Flavours Large", "Large Lollipop", "100g Assorted Flavours Small", "100g Assorted Flavours Large","Candy Cane", "100g Candy Canes"]] #makes the dictionary lowercase so the user input case doesn't matter

这一行不使字典小写，而是用小写candy_names列表替换它。如果您希望candy_names是小写的，那么只需调用

candy_names.lower()

声明它之后，然后创建的字典将小写candy_names作为键保存。

Answer 2

candy_order是一个包含字符串值的列表。

    if keep_ordering != "yes":
        for _candy, _number in zip(candy_order, number_order):
          # _candy: string
          # _number: int
          total += price_and_name[_candy] + _number
          # you are trying to index price_and_name using _candy which is a string
        print("Your total is $%f" % total)
    break

Answer 3

在尝试更新price_and_name以包含糖果名称的小写版本时，您将其从dict更改为list (正如@mozway的注释中指出的那样)，因此当您稍后尝试通过str键访问dict值时，它会给出问题中的错误。

另外，在不相关的情况下，total的计算应该使用乘法，而不是加法。

建议的更改：

如果您更改这一行：

price_and_name = dict(zip(candy_name, candy_price))

..。是这样的：

price_and_name = dict(zip([x.lower() for x in candy_name], candy_price))

..。并删除这一行：

  price_and_name = [price_and_name.lower() for price_and_name in ["Assorted Small Lollipops", "Assorted Flavours Small", "Assorted Flavours Large", "Large Lollipop", "100g Assorted Flavours Small", "100g Assorted Flavours Large","Candy Cane", "100g Candy Canes"]] #makes the dictionary lowercase so the user input case doesn't matter

..。并更改这一行：

      total += price_and_name[_candy] + _number

..。对此：

      total += price_and_name[_candy] * _number

..。看起来不错。