压痕问题

Question

我无法让这个python程序工作，每次运行它时，它会在第25行（即'else'循环）中出现“缩进时不一致使用制表符和空格”错误。我已经尝试了各种方法来解决这一切无济于事，所以想知道是否有人能解释我的问题。非常感谢您的时间。

questions = ["What does RAD stand for?",
        "Why is RAD faster than other development methods?",
        "Name one of the 3 requirements for a user friendly system",
        "What is an efficient design?",
        "What is the definition of a validation method?"]


answers = ["A - Random Applications Development, B - Recently Available Diskspace, C - Rapid Applications Development",
        "A - Prototyping is faster than creating a finished product, B - Through the use of CASE tools, C - As end user evaluates before the dev team",
        "A - Efficient design, B - Intonated design, C - Aesthetic design",
        "A - One which makes best use of available facilities, B - One which allows the user to input data accurately, C - One which the end user is comfortable with",
        "A - A rejection of data which occurs because input breaks predetermined criteria, B - A double entry of data to ensure it is accurate, C - An adaption to cope with a change external to the system"]

correctanswers = ["C", "B", "A", "A", "A"]

score = 0

for i in range(len(questions)):
    a = 1
    print (questions[a])
    print (answers[a])
    useranswer = (input("Please enter the correct answer's letter here:"))
    correctanswer = correctanswers[a]
    if useranswer is correctanswer:
            print("Correct, well done!")
            score = score + 1
        else:
            print("Incorrect, sorry!")

print("Well done, you scored" + score + "//" + int(len(questions)))

Answer 1

您正在混合制表符和空格，使用-tt运行python来检查：

python -tt scriptname.py

将编辑器配置为仅使用空格进行缩进。通常，有一个菜单选项可以将所有选项卡转换为空格。

显然，当您将代码粘贴到Stack Overflow窗口时，您已经可以看到您的else:行仅使用空格，但其他行使用了标签：

    if useranswer is correctanswer:
            print("Correct, well done!")
            score = score + 1
        else:
            print("Incorrect, sorry!")

因为Stack Overflow将标签渲染为4个空格。

Answer 2

缩进代码时， 使用制表符或空格。不要混合它们（即你不能在一行上使用制表符和下一行使用制表符。）

Answer 3

您的else应与if的缩进级别相同。

   if useranswer is correctanswer:
        print("Correct, well done!")
        score = score + 1
   else:
        print("Incorrect, sorry!")

Answer 4

至少在这个代码块上，你的if和else是不同的意图，它们应该是相同的。

if useranswer is correctanswer:
        print("Correct, well done!")
        score = score + 1
    else:
        print("Incorrect, sorry!")

应该是：

if useranswer is correctanswer:
        print("Correct, well done!")
        score = score + 1
else:
        print("Incorrect, sorry!")