python - 未解决的参考，我不知道为什么？答案

【问题标题】：python - Unresolved reference and I don' know why?python - 未解决的参考，我不知道为什么？
【发布时间】：2020-01-19 12:35:13
【问题描述】：

我正在尝试制作一个小程序，告诉您获得特定卡片的机会是多少，并询问您抽到了哪些卡片。当它询问绘制了哪张卡片时，它会在代码中显示未解决的引用，我不确定它的含义或为什么会这样说

cards = 52

ace = 4
queen = 4
king = 4
jack = 4

two = 4
three = 4
four = 4
five = 4
six = 4
seven = 4
eight = 4
nine = 4
ten = 4  

def ask_what_card_was_drawn():
    drawncard = input("What card did you draw?: ")
    if drawncard == ace:
        ask_what_card_was_drawn()
    elif drawncard == queen:
        queen == queen - 1
        cards == cards - 1
    elif drawncard == jack:

    #code kinda repeats itself here#

    #tried experimenting with -= 1 instead#
    elif drawncard == nine:
        nine == -1
        cards == cards - 1
    elif drawncard == "ten":
        ten -= 1
        cards -= 1
    else:
        print("Error")
    print("Cards left are: ")
    print("Cards = ", cards)
    print("     ace = ", ace)
    #kinda repeated itself again here aswell#
    print("     ten = ", ten)

    ask_what_card_was_drawn()

【问题讨论】：

你能复制准确的错误吗？
而且你甚至没有重现完整的代码。
我去粘贴整个代码，但是 stackoverflow 说我的帖子主要是代码所以我删除了几行以便我可以发布
谢谢乔丹，如果有帮助，我会尝试获取更新代码和错误的全屏截图
我只想说，如果我在工作面试中看到有人用“six = 4”这行代码编写代码，我就不会再看了......

标签： python python-3.x function playing-cards

【解决方案1】：

您的代码存在很多问题。第一个是在将全局变量映射到本地范围之前引用全局变量，从而生成UnboundLocalError。你需要告诉 Python 你正在使用全局变量，例如：

def ask_what_card_was_drawn():
    global cards, ace, queen, king, jack, two, three, four, five, size, seven, eight, nine, ten
    drawncard = input("What card did you draw?: ")
    ...

第二个问题是您使用== 分配值而不是=。第一个是检查相等性的条件，而第二个是为名称分配值。因此，例如，以下行：

queen == queen - 1

实际上被解释为False，因为queen 不等于queen - 1。你只需要像这样使用一个=：

queen = queen - 1

甚至更好：

queen -= 1

【讨论】：

【解决方案2】：

我发现了问题所在。在使 python 发疯的函数中设置和更改了变量。首先将所有变量设置为 GLOBAL 似乎可以解决它

cards = 52

ace = 4
queen = 4
king = 4
jack = 4
two = 4
three = 4
four = 4
five = 4
six = 4
seven = 4
eight = 4
nine = 4
ten = 4
def ask_what_card_was_drawn():
    drawn_card = str(input("What card did you draw?: "))
    global cards

    global ace
    global queen
    global king
    global jack

    global two
    global three
    global four
    global five
    global six
    global seven
    global eight
    global nine
    global ten
    if drawn_card == "ace":
        ace -= 1
        cards -= 1
    elif drawn_card == "queen":
        queen -= 1
        cards -= 1
    elif drawn_card == "jack":
        jack -= 1
        cards -= 1
    elif drawn_card == "king":
        king -= 1
        cards -= 1

【讨论】：