现在已经被困在试图解决问题一个小时了

Question

此代码应该给出错误消息：“错误，请重试！”如果输入的颜色不是红色、蓝色或黄色。它给了我错误消息，同时也给了我正确的输入，但我不明白为什么。

ColorOne = input('Enter the first primary color please ')
ColorTwo = input('Enter the second primary color please ')
if ColorOne != ('red' or 'blue' or 'yellow'):
        print('Error please try again!')
if ColorTwo != ('red' or 'blue' or 'yellow'):
        print('Error please try again!')
if ColorOne == ('red') and ColorTwo == ('blue'):
        print('Purple')
if ColorOne == ('red') and ColorTwo == ('yellow'):
        print('Orange')
if ColorOne == ('blue') and ColorTwo == ('yellow'):
        print('Green')
if ColorTwo == ('red') and ColorOne == ('blue'):
        print('Purple')
if ColorTwo == ('red') and ColorOne == ('yellow'):
        print('Orange')
if ColorTwo == ('blue') and ColorOne == ('yellow'):
        print('Green')

Answer 1

试试这个：

ColorOne = input('Enter the first primary color please ')
ColorTwo = input('Enter the second primary color please ')
if ColorOne not in ['red','blue','yellow']:
        print('Error please try again!')
if ColorTwo not in ['red','blue','yellow']:
        print('Error please try again!')
if ColorOne == ('red') and ColorTwo == ('blue'):
        print('Purple')
if ColorOne == ('red') and ColorTwo == ('yellow'):
        print('Orange')
if ColorOne == ('blue') and ColorTwo == ('yellow'):
        print('Green')
if ColorTwo == ('red') and ColorOne == ('blue'):
        print('Purple')
if ColorTwo == ('red') and ColorOne == ('yellow'):
        print('Orange')
if ColorTwo == ('blue') and ColorOne == ('yellow'):
        print('Green')

你的代码的问题在于逻辑，在现实世界（口语）中，你会说如果颜色不是红色、蓝色或黄色，那么就做一些事情，但在编程逻辑中，这不会那样工作。 !=（红色或蓝色或黄色）等于如果颜色不是红色、不是蓝色、也不是黄色，则执行某些操作。这就是利用德摩根定律。

Answer 2

解决了。

ColorTwo = input('Enter the second primary color please ')
if ColorOne not in ('red', 'blue', 'yellow'):
        print('Error please try again!')
if ColorTwo not in ('red', 'blue', 'yellow'):
        print('Error please try again!')
if ColorOne == ('red') and ColorTwo == ('blue'):
        print('Purple')
if ColorOne == ('red') and ColorTwo == ('yellow'):
        print('Orange')
if ColorOne == ('blue') and ColorTwo == ('yellow'):
        print('Green')
if ColorTwo == ('red') and ColorOne == ('blue'):
        print('Purple')
if ColorTwo == ('red') and ColorOne == ('yellow'):
        print('Orange')
if ColorTwo == ('blue') and ColorOne == ('yellow'):
        print('Green')

你需要这样检查

if ColorTwo not in ('red', 'blue', 'yellow'):

Answer 3

问题在于代码 ColorOne != ('red' or 'blue' or 'yellow'):。这不是检查变量是否是这些值之一的正确方法。您应该更改为 ColorOne not in ('red', 'blue', 'yellow'):

不管怎样，我做了一些改进。

ColorOne = input('Enter the first primary color please ')
ColorTwo = input('Enter the second primary color please ')
    
Colors = ('red','blue','yellow')

combination = set((ColorOne.strip().lower(), ColorTwo.strip().lower()))

if not combination.issubset(Colors):
    print('Error please try again!')
elif combination == {'blue','red'}:
    print('Purple')
elif combination == {'red','yellow'}:
    print('Orange')
elif combination == {'blue','yellow'}:
    print('Green')