Python验证循环异常：输入非法答案时未重复询问目标问题

你的循环验证失效是因为条件判断逻辑错误：比如if diabetes == 'y' or 'yes'这种写法，Python会把它解析成(diabetes == 'y') or 'yes'，而'yes'是一个非空字符串，永远被视为True，所以不管输入什么内容，第一个if条件都会成立，直接执行break，根本不会进入else分支提示用户重新输入。

1. 修复条件判断逻辑 #

把每个判断条件改成检查输入是否在允许的选项列表中，同时统一转为小写，兼容用户输入大写（比如Y/YES）的情况：

# Calculate Family Disease Scores

diabetes = ''
while True:
    diabetes = input('\n Do you have a family history of Diabetes? (Answer yes or no)').strip().lower()
    if diabetes in ['y', 'yes']:
        diabetesScore = 10
        break
    elif diabetes in ['n', 'no']:
        diabetesScore = 0
        break
    else:
        print('Please answer Yes or No')

cancer = ''
while True:
    cancer = input('\n Do you have a family history of cancer? (Answer yes or no)').strip().lower()
    if cancer in ['y', 'yes']:
        cancerScore = 10
        break
    elif cancer in ['n', 'no']:
        cancerScore = 0
        break
    else:
        print('Please answer Yes or No')

alzheimers = ''
while True:
    alzheimers = input('\n Do you have a family history of alzheimers? (Answer yes or no)').strip().lower()
    if alzheimers in ['y', 'yes']:
        alzheimersScore = 10
        break
    elif alzheimers in ['n', 'no']:
        alzheimersScore = 0
        break
    else:
        print('Please answer Yes or No')

# 计算总风险分
total_score = diabetesScore + cancerScore + alzheimersScore
print(f"\nTotal family disease risk score: {total_score}")

2. 优化代码（避免重复逻辑） #

三个问题的处理逻辑完全一致，可以封装成一个通用函数，减少代码冗余：

def get_family_history_score(disease_name):
    while True:
        response = input(f'\n Do you have a family history of {disease_name}? (Answer yes or no)').strip().lower()
        if response in ['y', 'yes']:
            return 10
        elif response in ['n', 'no']:
            return 0
        else:
            print('Please answer Yes or No')

# Calculate Family Disease Scores
diabetesScore = get_family_history_score('Diabetes')
cancerScore = get_family_history_score('cancer')
alzheimersScore = get_family_history_score('alzheimers')

total_score = diabetesScore + cancerScore + alzheimersScore
print(f"\nTotal family disease risk score: {total_score}")

关键改进点 #

• 使用.strip()去除输入前后的空格，避免用户输入空格导致判断失败
• 使用.lower()统一转为小写，兼容Y/YES/No等多种输入格式
• 用in ['y', 'yes']替代错误的or逻辑，确保只有输入符合选项时才会跳出循环

内容的提问来源于stack exchange，提问作者Sam Alzoubi