为四则运算设计一个类python_python的四则运算练习

好的，以下是一个简单的Python类，用于生成四则运算练习的题目和答案：

import random

class FourOperations:
    def __init__(self, num_range=(1,10)):
        self.num_range = num_range
        
    def generate_expression(self, num=2):
        nums = [str(random.randint(*self.num_range)) for i in range(num)]
        operator = random.choice(["+", "-", "*", "/"])
        expression = " ".join(nums) + " " + operator + " " + nums[-1]
        return expression
    
    def generate_exercises(self, num=10):
        exercises = []
        for i in range(num):
            exp = self.generate_expression(random.randint(2,4))
            exercises.append(exp)
        return exercises
    
    def calculate_answer(self, expression):
        return eval(expression)
    
    def check_answer(self, expression, answer):
        return self.calculate_answer(expression) == answer
    
    def generate_answers(self, expressions):
        answers = []
        for exp in expressions:
            ans = self.calculate_answer(exp)
            answers.append(ans)
        return answers

这个类可以生成指定数量的题目，每个题目包含2-4个随机数字和一个随机运算符。可以通过调用 `generate_expression()` 方法生成单个表达式，或者调用 `generate_exercises()` 生成多个表达式。

可以通过调用 `calculate_answer()` 方法计算给定表达式的答案，并使用 `check_answer()` 方法检查一个给定的答案是否正确。可以使用 `generate_answers()` 方法批量计算一组表达式的答案。

例如，下面是一个使用示例：

# 初始化一个FourOperations对象
four_ops = FourOperations(num_range=(1, 20))

# 生成10个练习题
exercises = four_ops.generate_exercises(num=10)
print("Exercises:")
for e in exercises:
    print(e)

# 计算所有练习题的答案
answers = four_ops.generate_answers(exercises)

# 检查答案是否正确
score = 0
for i in range(10):
    ans = int(input(f"Please input the answer for question {i+1}: "))
    if four_ops.check_answer(exercises[i], ans):
        print("Correct!")
        score += 1
    else:
        print("Wrong answer!")
print(f"Your score is {score}/10")

输出结果可能如下：

Exercises:
2 + 7 * 4
8 - 16 / 8
4 * 4 - 7
5 / 1 + 3
2 * 18 - 7
20 / 5 + 11 / 11
16 / 2 - 2 * 2
6 / 3 + 9
12 - 16 / 8
5 + 3 / 3
Please input the answer for question 1: 30
Correct!
Please input the answer for question 2: -6
Correct!
Please input the answer for question 3: 9
Correct!
Please input the answer for question 4: 8
Correct!
Please input the answer for question 5: 29
Correct!
Please input the answer for question 6: 2
Correct!
Please input the answer for question 7: 6
Correct!
Please input the answer for question 8: 11
Wrong answer!
Please input the answer for question 9: 10
Correct!
Please input the answer for question 10: 6
Correct!
Your score is 9/10