我如何在一个小测验中对每一个问题实现一个定时器？

Question

我试着做一个小测验，其中一个标准是限制测验中每一个问题的解决时间。我查阅了一些教程，但有些需要输入x秒才能使计时器停止，而另一些则更像是秒表.

我想知道，如果30秒的周期已经结束，那么当问题被打印出来，跳到下一个问题时，我该怎么做呢？我对计时器功能一无所知，甚至无法将它们实现到我的代码中。有人能给我一些提示吗?这样我就可以在实现一个工作计时器方面取得更大的进步了吗？

谢谢!

编辑部分如下:我想在编码上实现的计时器：

import time
import threading

def atimer():
    print("Time's up.")

a_timer = threading.Timer(10.0, atimer)
a_timer.start()
print("")

这就是我试图将计时器实现到的全部编码。我注意到，当我试图定义qtimer以只打印1到2行语句时，计时器可以工作，但我希望计时器停止，转到第二个问题，或者停止，让用户再次尝试重试这个问题，所以我尝试在定义之后附加一堆代码，但它没有工作。我知道我在这里很可能做错了什么，因为我对时间或线程函数不太熟悉。有解决办法吗？

def qtimer():
    print("I'm sorry but your time is up for this question.")
    print("You may have another attempt if you wish to, with reduced marks allocated.")
    response1 = input("Type 'Yes' for another attempt, anything else to skip: ")
    if response1 == "Yes":
        Answ = input("Which option would you go for this time?: ")
        Answ = int(Answ)
        if possible[Answ - 1] == qaItem.corrAnsw:
            print("Your answer was correct.")
            corr += 1
            marks += 0.5 * qaItem.diff
        else:
            print("Your answer was wrong.")
            print("Correct answer was: " + qaItem.corrAnsw)
            print("Explanation: " + qaItem.expl)
            print("")
    else:
        print("Correct answer was: " + qaItem.corrAnsw)
        print("Explanation: " + qaItem.expl)
        print("")

class A:
  def __init__(self, question, correctAnswer, otherAnswers, difficulty, explanation):
    self.question = question
    self.corrAnsw = correctAnswer
    self.otherAnsw = otherAnswers
    self.diff = difficulty
    self.expl = explanation

qaList = [A("What is COVID-19?", "Coronavirus Disease 2019", ["Wuhan virus", "I don't understand...", "Coronavirus Disease v19"], 1, "Explanation 1"),
A("What describes COVID-19?", "A disease", ["A virus", "A parasite", "A bacteriophage"], 1, "Explanation 2"),
A("What causes COVID-19?", "SARS-CoV-2", ["Coronavirus", "Mimivirus", "Rubeola Virus"], 1, "Explanation 3"),
A("Which of the following is used in COVID-19 treatment?", "Lopinavir / Ritonavir ", ["Midazolam / Triazolam", "Amiodarone", "Phenytoin"], 2, "Explanation 4"),
A("Which of the following receptors is used by COVID-19 to infect human cells?", "ACE-2 Receptors", ["ApoE4 Receptors", "TCR Receptors", "CD28 Receptors"], 3, "Explanation 5")]

corr = 0
marks = 0
random.shuffle(qaList)
for qaItem in qaList:
    q_timer = threading.Timer(5.0, qtimer)
    q_timer.start()
    print(qaItem.question)
    print("Possible answers are:")
    possible = qaItem.otherAnsw + [qaItem.corrAnsw]
    random.shuffle(possible)
    count = 0
    while count < len(possible):
        print(str(count+1) + ": " + possible[count])
        count += 1
    print("Please enter the number of your answer:")
    Answ = input()
    Answ = str(Answ)
    while not Answ.isdigit():
        print("That was not a number. Please enter the number of your answer:")
        Answ = input()
        Answ = int(Answ)
    Answ = int(Answ)
    while Answ > 4 or Answ < 1:
        print("That number doesn't correspond to any answer. Please enter the number of your answer:")
        Answ = input()
        Answ = int(Answ)
    if possible[Answ-1] == qaItem.corrAnsw:
        print("Your answer was correct.")
        corr += 1
        marks += 1 * qaItem.diff
    else:
        print("Your answer was wrong.")
        response = input("Would you want to try again? If so, input 'Yes' to attempt it again, if not just input whatever!")
        if response == "Yes":
            Answ = input("Which option would you go for this time?: ")
            Answ = int(Answ)
            if possible[Answ - 1] == qaItem.corrAnsw:
                print("Your answer was correct.")
                corr += 1
                marks += 0.5 * qaItem.diff
            else:
                print("Your answer was wrong.")
                print("Correct answer was: " + qaItem.corrAnsw)
                print("Explanation: " + qaItem.expl)
                print("")
        else:
            print("Correct answer was: " + qaItem.corrAnsw)
            print("Explanation: " + qaItem.expl)
            print("")

print("You answered " + str(corr) + " of " + str(len(qaList)) + " questions correctly.")
print("You have achieved a total score of " + str(marks) + ".")

Answer 1

即使有计时器，主线程也不能继续等待用户输入一个数字；因此，如果用户什么也不做，计时器函数就会运行，一旦完成，主线程仍在等待输入

print("Please enter the number of your answer:")
Answ = input() 

您可以有一个定时器线程设置的全局标志，告诉主线程在计时器代码中将接收到的输入作为response1来处理，还可以有一个标志告诉计时器收到了答案，等等，这样很快就变得相当复杂。

因此，不要试图通过计时器和主线程之间的通信来绕过对input的阻塞调用，而是从https://stackoverflow.com/a/22085679/1527中选择非阻塞输入示例，并在时间成熟时尽早停止循环。

def timed_input(msg, timeout=10):
    kb = KBHit()

    print(msg)

    end_time = time.time() + timeout
    warn_time = 5

    result = None

    while True:

        if kb.kbhit():
            c = kb.getch()
            if '0' <= c <= '9':
                result = int(c)
                break                
            print(c)

        if time.time() > end_time:
            print('time is up')
            break

        if time.time() > end_time - warn_time:
            print(f'{warn_time}s left')
            warn_time = warn_time - 1

    kb.set_normal_term()

    return result


# Test    
if __name__ == "__main__":
    result = timed_input('Enter a number between 1 and 4')
    if result is None:
        print('be quicker next time')
    elif 1 <= result <= 4:
        print('ok')
    else: 
        print(f'{result} is not between 1 and 4')

还请注意，将代码分解成更小的函数有助于使代码更容易理解，测试的逻辑不需要知道超时的逻辑。