如何将函数中的变量更改为在主代码中使用？

Question

我对Python非常陌生，我很难搞清楚以下几点：

import random
import sys

print("Welcome to this Maths quiz.")
playerName = str(input("Please enter your name: "))
playerAge = int(input("Please enter your age: "))
if playerAge < 11:
    print("This quiz is not for your age.")
    sys.exit(0)
else :
    print("Great! Let's begin.\n")

quizQuestions = ["9(3+8)", "7+9*8", "(9+13)(9-5)", "50*25%", "104-4+5*20"]
quizAnswers = ["99", "79", "88", "12.5", "0"]
quizSync = list(zip(quizQuestions, quizAnswers))
random.shuffle(quizSync)
quizQuestions, quizAnswers = zip( * quizSync)
questionNumber = 1
quizScore = 0

def displayQuestion(quizQuestions, quizAnswers, questionNumber, quizScore):
    print("Question " + str(questionNumber) + ": " + quizQuestions[questionNumber - 1] + "\n")
    questionAnswer = str(input())
    if questionAnswer == quizAnswers[questionNumber - 1]:
        print("\nCorrect!\n")
        quizScore += 1
    else :
        print("\nIncorrect! The answer is: " + quizAnswers[questionNumber - 1] + "\n")

while questionNumber < 6:
    displayQuestion(quizQuestions, quizAnswers, questionNumber, quizScore)
    questionNumber += 1

print("You have a total score of: "+str(quizScore))

如果玩家问对了问题，我希望函数"quizScore“中的变量"displayQuestion”增加1。然而，在测试结束后，最后的打印函数总是打印分数为0，即使玩家的问题是正确的。

Answer 1

虽然这不是最短的答案，也就是使用另一个全局变量。相反，它将向您展示如何通过使用被认为是有害的避免使用全局变量( 面向对象编程(OOP) )。为了实现这一点，您问题中的大部分代码可以封装到下面名为MathQuiz的单个类中。

除了消除几乎所有的全局变量，它还提供了一个可用的模板，您可以创建任意数量的独立数学测试。

import random
import sys

class MathQuiz:
    def __init__(self, questions, answers):
        quizSync = list(zip(questions, answers))
        random.shuffle(quizSync)
        self.quizQuestions, self.quizAnswers = zip(*quizSync)
        self.quizScore = 0

        print("Welcome to this Maths quiz.")
        self.playerName = str(input("Please enter your name: "))
        self.playerAge = int(input("Please enter your age: "))
        if self.playerAge > 10:
            print("Great! Let's begin.\n")
        else :
            print("This quiz is not for your age.")
            sys.exit(0)

    def run(self):
        for questionNumber in range(len(self.quizQuestions)):
            self._displayQuestion(questionNumber)

        print("You have a total score of: " + str(self.quizScore))

    def _displayQuestion(self, questionNumber):
        print("Question " + str(questionNumber) + ": "
              + self.quizQuestions[questionNumber-1]
              + "\n")
        questionAnswer = str(input())
        if questionAnswer == self.quizAnswers[questionNumber-1]:
            print("\nCorrect!\n")
            self.quizScore += 1
        else :
            print("\nIncorrect! The answer is: "
                  + self.quizAnswers[questionNumber-1]
                  + "\n")

quiz = MathQuiz(["9(3+8)", "7+9*8", "(9+13)(9-5)", "50*25%", "104-4+5*20"],
                ["99", "79", "88", "12.5", "0"])
quiz.run()

Answer 2

您必须在函数中声明它为全局变量，以便它可以修改全局范围中的变量。

def displayQuestion(quizQuestions, quizAnswers, questionNumber):
    global quizScore    
    ...
    quizScore += 1

尽管如此，如果可以的话，通常应该避免全局变量，并尝试重新设计程序，将变量作为参数和返回值传递，或者使用类封装数据。