Python中while循环能否设置多值哨兵值？循环异常问题求助

你的代码出现无限循环的核心问题是while条件的逻辑错误：
while favorite != 'done' or 'quit' 这行代码里，'quit'是一个非空字符串，在Python的布尔判断中会被直接判定为True。不管favorite的值是什么，整个条件都会变成「某个值 or True」，结果永远是True，循环自然停不下来。

正确实现方式 #

方式一：用not in判断哨兵集合

把两个终止值放在一个集合（或列表）里，判断输入不在这个集合内就继续循环，写法更简洁直观：

favorites = dict()
name = input('What is your name?\n')
favorite = input('What favorite do you want to enter? (quit or done to end)\n')
while favorite not in {'done', 'quit'}:
    favorite_item = input(f'What is your favorite {favorite}?\n')
    favorites[favorite] = favorite_item
    favorite = input('What favorite do you want to enter? (quit or done to end)\n')

方式二：明确逻辑判断（用and连接）

如果不想用集合，也可以把两个判断条件用and连接，表示必须同时不满足两个终止条件才继续循环：

favorites = dict()
name = input('What is your name?\n')
favorite = input('What favorite do you want to enter? (quit or done to end)\n')
while favorite != 'done' and favorite != 'quit':
    favorite_item = input(f'What is your favorite {favorite}?\n')
    favorites[favorite] = favorite_item
    favorite = input('What favorite do you want to enter? (quit or done to end)\n')

额外优化：减少重复代码 #

可以把重复出现的输入提示提取成变量，让代码更简洁易维护：

favorites = dict()
name = input('What is your name?\n')
prompt = 'What favorite do you want to enter? (quit or done to end)\n'
favorite = input(prompt)
while favorite not in {'done', 'quit'}:
    favorite_item = input(f'What is your favorite {favorite}?\n')
    favorites[favorite] = favorite_item
    favorite = input(prompt)

内容的提问来源于stack exchange，提问作者Samantha Groenwold