在python 3.6中列出和转换用户输入

Question

您好，我无法弄清楚如何将我的总购物价格加在一起并显示总数。我搜索这个，我无法找到我正在寻找:( 谢谢！

print("Hello this is your shopping list!")

shopList = []
shoppingTotal = []
sumOfAllNumbers = sum(shoppingTotal)

maxLengthList = 2
while len(shopList) < maxLengthList:
    item = input("what do you need today? Add your item: ")
    shopList.append(item)
    price = int(input("How much can you spend?"))
    shoppingTotal.append(price)
    print(shopList)
    print(shoppingTotal)
print("This is your shopping list")
print(shopList)
print(sumOfAllNumbers + 'This will be your budget for today')

Answer 1

您的问题是，您在拥有完整列表之前已定义sumOfAllNumbers。当你说：

sumOfAllNumbers = sum(shoppingTotal)

在您设置时，

sumOfAllNumbers将设置为列表shoppingTotal 中所有值的总和。在你的代码中，你正在做：

shoppingTotal = []
sumOfAllNumbers = sum(shoppingTotal)

用它们的值替换变量，我们可以看到你正在做的是：

sumOfAllNumbers = sum（[]）

显然是0。

您应该做的是在> 之后将列表加上>，并为其添加价格。

此外，您无法直接将sumOfAllNumbers添加到字符串中 - 虽然可以添加数字和字符串，但Python不会自动转换值以将其添加到另一个 - 所以您需要首先使用str()函数手动转换sumOfAllNumbers。

所以你的代码应该是这样的：

print("Hello this is your shopping list!")

shopList = []
shoppingTotal = []

maxLengthList = 2
while len(shopList) < maxLengthList:
    item = input("what do you need today? Add your item: ")
    shopList.append(item)
    price = int(input("How much can you spend?"))
    shoppingTotal.append(price)
    print(shopList)
    print(shoppingTotal)


print("This is your shopping list")
print(shopList)

sumOfAllNumbers = sum(shoppingTotal)
print(str(sumOfAllNumbers) + 'This will be your budget for today')

此外，最后一点：您的变量名称不是Pythonic。 Python中的常规做法是使用snake_case而不是camelCase。因此sumOfAllNumbers应该被称为sum_of_all_numbers。