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我正在开发一个打开文件“answer.txt”的程序。该文件模拟学生对测试的回答。该程序然后将文件与 answerKey 进行比较。它逐行打印答案键与学生的答案。它会记录好答案和坏答案。最后它打印一个分数。我可以让这个程序使用两个不同的答案键，但是当我尝试从文件中提取答案时，我得到了太多的输出。它跳过文件中的第一个答案。然后它只来回打印来自应答键的 B、D。学生方从第二个答案开始打印，然后跳过所有其他答案。

我的代码：

def main():
    try:
        answerKey = ['B', 'D', 'A', 'A', 'C', 'A', 'B', 'A', 'C', 'D', 'B', 'C',\
                 'D', 'A', 'D', 'C', 'C', 'B', 'D', 'A']
        index = 0
        numCorrect = 0
        answer_file = open('answers.txt', 'r')

        studentExam = answer_file.readline()

        print('Correct\tYour\tStatus\nAns.\tAns.\n-----------------------\n')
        while studentExam != "":
            problem_number = index + 1
            studentExam = studentExam.rstrip("\n")

            studentExam = answer_file.readline()

            for answerLine, studentLine in zip (answerKey, studentExam):
                answer = answerLine.split()
                studentAnswer = studentLine.split()

                if studentAnswer != answer:
                    print( 'You got that question number', index + 1, 'wrong\n the correct answer was' ,answer, 'but you answered' , studentAnswer)
                    index += 1
                else:
                    numCorrect += 1
                    index += 1

        grade = int((numCorrect / 20) * 100)

        print (' The number of correctly answered questions: ', numCorrect)

        print (' The number of incorrectly answered questions: ', 20 - numCorrect)

        print (' Your grade is', grade, '%')

        if grade <= 75:
                    print (' You have not passed ')
        else:
                    print (' Congrats you have passed ')
    except IOError:
        print("The file could not be found")
    except IndexError:
        print("There was an indexing error")
    except:
        print("An error occurred")
main()

我的输出：

You got that question number 1 wrong
 the correct answer was ['B'] but you answered ['D']

You got that question number 2 wrong
the correct  answer was ['D'] but you answered []

You got that question number 3 wrong
 the correct answer was ['B'] but you answered ['A']

You got that question number 4 wrong
 the correct answer was ['D'] but you answered []

You got that question number 5 wrong
 the correct answer was ['B'] but you answered ['A']

You got that question number 6 wrong
 the correct answer was ['D'] but you answered []

You got that question number 7 wrong
 the correct answer was ['B'] but you answered ['C']

You got that question number 8 wrong
 the correct answer was ['D'] but you answered []

You got that question number 9 wrong
 the correct answer was ['B'] but you answered ['A']

You got that question number 10 wrong
 the correct answer was ['D'] but you answered []

You got that question number 12 wrong
 the correct answer was ['D'] but you answered []

You got that question number 13 wrong
 the correct answer was ['B'] but you answered ['A']

You got that question number 14 wrong
 the correct answer was ['D'] but you answered []

You got that question number 15 wrong
 the correct answer was ['B'] but you answered ['C']

You got that question number 16 wrong
 the correct answer was ['D'] but you answered []

You got that question number 17 wrong
 the correct answer was ['B'] but you answered ['C']

You got that question number 18 wrong
 the correct answer was ['D'] but you answered []

You got that question number 19 wrong
 the correct answer was ['B'] but you answered ['C']

You got that question number 20 wrong
 the correct answer was ['D'] but you answered []

You got that question number 21 wrong
 the correct answer was ['B'] but you answered ['C']

You got that question number 22 wrong
 the correct answer was ['D'] but you answered []

You got that question number 23 wrong
 the correct answer was ['B'] but you answered ['D']

You got that question number 24 wrong
 the correct answer was ['D'] but you answered []

You got that question number 25 wrong
 the correct answer was ['B'] but you answered ['A']

You got that question number 26 wrong
 the correct answer was ['D'] but you answered []

You got that question number 27 wrong
 the correct answer was ['B'] but you answered ['D']

You got that question number 28 wrong
 the correct answer was ['D'] but you answered []

You got that question number 29 wrong
 the correct answer was ['B'] but you answered ['C']

You got that question number 30 wrong
 the correct answer was ['D'] but you answered []

You got that question number 31 wrong
 the correct answer was ['B'] but you answered ['C']

You got that question number 32 wrong
 the correct answer was ['D'] but you answered []

You got that question number 34 wrong
 the correct answer was ['D'] but you answered []

You got that question number 35 wrong
 the correct answer was ['B'] but you answered ['D']

You got that question number 36 wrong
 the correct answer was ['D'] but you answered []

You got that question number 37 wrong
 the correct answer was ['B'] but you answered ['D']

You got that question number 38 wrong
 the correct answer was ['D'] but you answered []

 The number of correctly answered questions:  2
 The number of incorrectly answered questions:  18
 Your grade is 10 %

它没有比较正确的数据，请帮我纠正这个问题。只有 20 个答案，文件中的答案如下所示：

B
D
A
A
C
A
B
A
C
C
C
C
D
A
D
C
C
B
D
D

每个都有自己的路线。因此，我尝试使用循环来遍历答案键中的每个答案，并将其与该文件中的每个答案进行比较。谁能告诉我我的python代码有什么问题？

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2 回答 2

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你的算法不是你所期望的。您正在使用 循环浏览文件readline，然后对于该文件中的每一行，您都尝试遍历答案键。文件中的每一行都返回两个字符 ( 'B\n')，即成绩和换行符。当你做这for answerLine, studentLine in zip (answerKey, studentExam):行时，你正在zip用 2 元素 studentExam 输入长答案键（记住字符串是可迭代的），因此你只看到第一个回答键的人（第二个有一个空白的学生答案。

我建议在算法开始时一次性阅读学生的答案，然后zip在完整列表中使用。那会给你你想要的。

PS，你可能想要这个：

answer = answerLine.strip()
studentAnswer = studentLine.strip()

而不是这个：

answer = answerLine.split()
studentAnswer = studentLine.split()
于 2013-04-25T21:46:20.060 回答
0

无需遍历文件，而是一次将文件全部读入列表中。然后，您还想清理数据行。这是通过以下方式完成的：

answers = open('answers.txt', 'r').readlines()
answers = [answer.strip() for answer in answers]

这使您的while循环变得毫无意义，因为所有这些工作都被考虑在内。

一旦我们有了它，就是使用该列表的问题。

for answerLine, studentLine in zip(answerKey, answers):

这将为您提供以下输出（如果放置正确）：

Correct    Your    Status
Ans.    Ans.
-----------------------

('You got that question number', 10, 'wrong\n the correct answer was', ['D'], 'but you answered', ['C'])
('You got that question number', 11, 'wrong\n the correct answer was', ['B'], 'but you answered', ['C'])
('You got that question number', 20, 'wrong\n the correct answer was', ['A'], 'but you answered', ['D'])
(' The number of correctly answered questions: ', 17)
(' The number of incorrectly answered questions: ', 3)
(' Your grade is', 85, '%')
Congrats you have passed

另外，我强烈反对使用空except块。这将使调试您的代码成为一场噩梦，因为您将无法确定哪里出了问题以及哪里出了问题。

于 2013-04-25T21:49:28.517 回答