python：小学算术测验-将结果保存到.txt文件

Question

my task is to create a small quiz for primary school children. It asks them randomly generated questions then outputs their result. The program works perfectly well up until that point. For my task I must store the users 'username' and their 'correctAnswers' onto the a '.txt' file. The program seems to work but nothing is stored onto 'classScores.txt' file. Im quite new to coding so go easy on me. Any help would be appreciated :)

import random
import math

def test():
    num1=random.randint(1, 10)
    num2=random.randint(1, num1)

    ops = ['+','-','*']
    operation = random.choice(ops)

    num3=int(eval(str(num1) + operation + str(num2)))

    print ("What is {} {} {}?".format(num1, operation, num2))
    userAnswer= int(input("Your answer:"))
    if userAnswer != num3:
        print ("Incorrect. The right answer is {}".format(num3))
        return False
    else:
        print("correct")
        return True

username=input("What is your name?")
print ("Welcome {} to the Arithmetic quiz".format(username))

correctAnswers=0
for question_number in range(10):
    if test():
        correctAnswers +=1

print("{}: You got {} answers correct".format(username, correctAnswers))

my_file = open("classScores.txt", "a")
my_file.write("{}:{}".format(username,correctAnswers))

Answer 1

 my_file = open("classScores.txt", "a") my_file.write("{}:{}".format(username,correctAnswers)) 

The program seems to work but nothing is stored onto 'classScores.txt' file.

Your code will correctly write to the file--but it's good practice to close a file after you are done with it. As pointed out by Antti Haapala in the comments, you should do this:

with open("classScores.txt", "a") as my_file:  #my_file is automatically closed after execution leaves the body of the with statement
    username = 'Sajjjjid'
    correct_answers = 3

    my_file.write("{}:{}\n".format(username,correct_answers))

Im quite new to coding

eval(str(num1) + operation + str(num2))

Typically, the rule for beginners is:

Never, ever use eval().

Here are some better alternatives:

def test():
    num1 = random.randint(1, 10)
    num2 = random.randint(1, num1)

    def add(x, y):
        return x+y

    def sub(x, y):
        return x-y

    def mult(x, y):
        return x*y

    ops = {
        '+': add,
        '-': sub,
        '*': mult,
    }

    keys = list(ops.keys()) #=> ['+', '*', '-']
    rand_key = random.choice(keys)  #e.g. '*' 
    operation = ops[rand_key]  #e.g. mult

    correct_result = operation(num1, num2)

If you define a function, then use the function name without the trailing () , then the function is a value, just like the number 1, and the function can be assigned to a variable--just like any other value. When you want to execute a function stored in a variable, you use the trailing () after the variable name:

def func():
    print('hello')

my_var = func
my_var()  #=>hello

python also lets you create anonymous(unnamed) functions like this:

my_func = lambda x, y: x+y
result = my_func(1, 2)
print(result) #=>3

Why would you ever need to do that? Well, it can make your code more compact:

def test():
    num1 = random.randint(1, 10)
    num2 = random.randint(1, num1)

    ops = {
        '+': lambda x, y: x + y,  #You can define the function right where you want to use it.
        '-': lambda x, y: x - y,
        '*': lambda x, y: x * y,
    }

    keys = list(ops.keys()) ##=> ['+', '*', '-']
    rand_key = random.choice(keys)  #e.g. '*' 
    operation = ops[rand_key]  #e.g. lambda x, y: x*y

    correct_result = operation(num1, num2)

But, it turns out that python defines all those functions for you--in the operater module . So, you can make your code even more compact, like this:

import random
import math
import operator as op

def test():
    num1 = random.randint(1, 10)
    num2 = random.randint(1, num1)

    ops = {
        '+': op.add,  #Just like the add() functions defined above
        '-': op.sub,
        '*': op.mul,
    }

    keys = list(ops.keys()) #=> ['+', '*', '-']
    rand_key = random.choice(keys)  #e.g. '-'
    operation = ops[rand_key]  #e.g. op.sub

    correct_result = operation(num1, num2)

Here is a complete example with some other improvements:

import random
import math
import operator as op

def test():
    num1 = random.randint(1, 10)
    num2 = random.randint(1, num1)

    ops = {
        '+': op.add,
        '-': op.sub,
        '*': op.mul,
    }

    keys = list(ops.keys()) ##=> ['+', '*', '-']
    rand_key = random.choice(keys)  #e.g. '+' 
    operation = ops[rand_key]  #e.g. op.add

    correct_result = operation(num1, num2)

    print ("What is {} {} {}?".format(num1, rand_key, num2))
    user_answer= int(input("Your answer: "))

    if user_answer != correct_result:
        print ("Incorrect. The right answer is {}".format(correct_result))
        return False
    else:
        print("Correct!")
        return True

username = input("What is your name? ")
print("Hi {}! Welcome to the Arithmetic quiz...".format(username))

correct_answers = 0
num_questions = 3

for i in range(num_questions):
    if test():
        correct_answers +=1


print("{}: You got {}/{} questions correct.".format(
    username, 
    correct_answers, 
    num_questions,
    #'question' if (correct_answers==1) else 'questions'
))

Answer 2

with open("classCores.txt","a+") as f:
    f.write("{}:{}".format(username,correctAnswers))

Opened in a+ mode for avoid overwriting the file. The problem is in your codes, you forgot to close your file. However, I suggest you use with open() method which is way better than open() .