Question

当用户完成测验时，我试图扩展字典。我希望仅为用户存储最后三个分数，但当我尝试将其添加到空字典时我得到KeyError，当我尝试将分数作为列表实现时，我得到一个不可用的列表错误

studentScores = {}

def quiz():
    print("WELCOME TO THE MATH QUIZ\n")
    global student
    student = input("What is your name? ")
    global classname
    classname = input("Which class are you in? (1, 2, 3) ")
    global score
    score = 0

def addDict():
    global student
    global classname
    global score
    score = str(score)
    studentScores[student + classname, score]
    print(studentScores)

Answer 1

如评论中所述，问题出现在这一行：

studentScores[student + classname, score]

这一行的作用：它创建(student + classname, score)的元组，并使用该元组作为字典的键。由于该密钥不存在，因此会引发异常。

>>> student = "foo"
>>> classname = "bar"
>>> score = 0
>>> studentScores = {}
>>> studentScores[student + classname, score]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: ('foobar', 0)

相反，您只想使用student + classname作为键，将赋值为score。

>>> studentScores[student + classname] = score
>>> studentScores
>>> {'foobar': 0}

扩展时的字典KeyError

1 个答案: