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Python Dates and Times in Python Let's Build a Timed Quiz App Taking The Quiz

Asher Orr
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.a{fill-rule:evenodd;}techdegree
Asher Orr
Python Development Techdegree Student 3,496 Points

How do I correctly reference a variable within a method (OOP)?

Hi everyone! In the "summary" method (at the bottom of the file quiz_wf.py), I'm trying to print out how many seconds it took to answer each question.

I'm working with 2 files:

File 1: questions.py

class Question:
    answer = None
    text = None


class Add(Question):
    def __init__(self, num1, num2):
        self.text = '{} + {}'.format(num1, num2)
        self.answer = num1 + num2

class Multiply(Question):
    def __init__(self, num1, num2):
        self.text = '{} x {}'.format(num1, num2)
        self.answer = num1 * num2

File 2: quiz_wf.py

import datetime
import random

from questions import Add, Multiply


class Quiz:
    questions = []
    answers = []


    def __init__(self):
        question_types = (Add, Multiply)
        num_questions = int(input("How many questions would you like on the quiz? "))
        starting_range = int(input("For all your questions, what's the lowest number you'd like to work with? "))
        ending_range = int(input("For all your questions, what's the highest number you'd like to work with? "))
        for _ in range(num_questions):
            num1 = random.randint(starting_range, ending_range)
            num2 = random.randint(starting_range, ending_range)
            question = random.choice(question_types)(num1, num2)
            self.questions.append(question)


    def take_quiz(self):
        self.start_time = datetime.datetime.now()
        for question in self.questions:
            self.answers.append(self.ask(question))
        else:
            self.end_time = datetime.datetime.now()
        return self.summary()


    def ask(self, question):
        correct = False
        question_start = datetime.datetime.now()
        answer = input(question.text + ' = ')
        if answer == str(question.answer):
            correct = True
        question_end = datetime.datetime.now()
        return correct, question_end - question_start


    def total_correct(self):
        total = 0
        for answer in self.answers:
            if answer[0]:
                total += 1
        return total

    def summary(self):
        print(f"You got {self.total_correct()} out of {len(self.questions)} right.")
        print(f"It took you {(self.end_time - self.start_time).seconds} seconds for the whole quiz.")
        print("For each question, this is how many seconds you took: ")


my_quiz = Quiz()
my_quiz.take_quiz()

I am new to OOP, and I am struggling with this task.

In my "summary" method, I tried this code:

 def summary(self):
        print(f"You got {self.total_correct()} out of {len(self.questions)} right.")
        print(f"It took you {(self.end_time - self.start_time).seconds} seconds for the whole quiz.")
        print("For each question, this is how many seconds you took: ")
        for question in self.questions:
                print(f'Question #{self.questions.index(question)+1}: {self.question_end - self.question_start}.seconds')

I get this AttributeError, though:

AttributeError: 'Quiz' object has no attribute 'question_end'. Did you mean: 'questions'?

Can anyone help me with properly referencing the question_start and question_end variables in the "ask" method?

Thank you for reading!

1 Answer

Steven Parker
Steven Parker
216,810 Points

As the message says, there's no "question_end" in the "questions" list. But the "ask" method returns a tuple containing the result status and a timedelta for the elapsed time, and that tuple gets appended to the "answers" list in "take_quiz".

So you can access the time from the "seconds" attribute of the timedelta. It might also be easier to have the loop step directly through the index values (instead of searching for them), for example:

        for i in range(len(self.questions)):
            print(f'Question #{i+1}: {self.answers[i][1].seconds}')
Asher Orr
seal-mask
.a{fill-rule:evenodd;}techdegree
Asher Orr
Python Development Techdegree Student 3,496 Points

This makes so much sense! Thank you, Steven. I didn't perceive the last line (return correct, question_end - question_start) in the "ask" method as a tuple.

I see now that you can loop through the range of self.questions, then use the answers list to display the time required for each. Thanks again!