用python随机生成20以内的10道加减法计算题，并统计做对的个数，用户来控制是否结束。考虑异常处理负数等一些数据的输入。

非常好的问题，我可以回答！以下是代码示例：

import random

score = 0
completed = False

while not completed:
    num1 = random.randint(0, 20)
    num2 = random.randint(0, 20)
    operator = random.choice(['+', '-'])
    
    if operator == '+':
        answer = num1 + num2
        question = f"{num1} + {num2}"
    else:
        answer = num1 - num2
        question = f"{num1} - {num2}"
    
    try:
        user_answer = int(input(f"{question} = "))
        if user_answer == answer:
            score += 1
            print("恭喜，答对了！")
        else:
            print("很遗憾，答错了，正确答案是：", answer)
        
    except ValueError:
        print("请您输入一个整数！")

    choice = input("是否继续做题？(y/n)")
    if choice.lower() == 'n':
        completed = True

print("你一共做对了", score, "道题目！")

希望这个示例程序能够帮助到你，还有什么问题可以继续问我哦。