Python while循环布尔仅显示为True

Question

I'm having trouble. I want the code to loop through and ask 'Hey, are you hungry?' but only if the hungry variable isn't True or False . However, whatever answer I type in, it acts as if it's True .

In my head, if I type a variation of yes, then hungry should be True and the code should stop. If I type a variation of no then the code should be False and stop. If I type neither of these then hungry will not be True or False and should loop through, asking the question again.

hungry = None
while hungry != True or False:
    hungry = input('Hey, are you hungry?')
    if hungry == 'yes' or 'ye' or 'y' or 'yeah':
        print ('oh you hungry huh')
        hungry = True
    elif hungry == 'no' or 'n' or 'nah' or 'nope':
        print ('no food for you then')
        hungry = False
    else:
        print ('its a simple yes or no question pls')

Answer 1

You have a few issues here, not least is using the same variable name for a few different purposes which is not good style, and also not really using the control flow primitives in python - look it up ( https://wiki.python.org/moin/WhileLoop ).

A concise a working solution would look as follows:

while True:
    hungry = input('hungry?')
    if hungry in ('y','yes'):
        print('Eat up')
        break
    elif hungry in ('n','no'):
        print('Ok not hungry')
        break
    else:
        print('You need to tell me')

What we've got above is:

• We're starting an infinite loop (while True)

• We're assigning the user input to the hungry variable - and that's all it holds

• If the user enters a variant on 'yes' or 'no' it prints a response and breaks out of the while loop

• if they don't provide a yes/no answer, it goes back to the beginning of the loop again (ie no break)

Answer 2

You can't say if x == a or b or c in Python and have it do what you want. You need to use if x in [a, b, c] instead.

Answer 3

The condition hungry == 'yes' or 'ye' or 'y' or 'yeah' doesn't check if any of hungry == 'yes' or hungry == 'ye' or hungry == 'y' or hungry == 'yeah' is true. It checks (hungry == yes) or 'ye' or 'y' or 'yeah' (and nothing but hungry == yes has a truth value)

Similarly hungry != True or False is checking (hungry != True) or False so the False part of the conditional doesn't do anything.

You should write it as:

hungry = None
while hungry not in (True, False):
    hungry = input('Hey, are you hungry?')
    if hungry in ('yes', 'ye', 'y', 'yeah'):
        print ('oh you hungry huh')
        hungry = True
    elif hungry in ('no', 'n', 'nah', 'nope'):
        print ('no food for you then')
        hungry = False
    else:
        print ('its a simple yes or no question pls')

Answer 4

Try it this way:

hungry = None
while hungry not in (True, False):
    hungry = input('Hey, are you hungry?')
    if hungry in ('yes', 'ye', 'y', 'yeah'):
        print('oh you hungry huh')
        hungry = True
    elif hungry in ('no', 'n', 'nah', 'nope'):
        print('no food for you then')
        hungry = False
    else:
        print('its a simple yes or no question pls')

Answer 5

This is because you are writing code like it is english. When you are comparing a variable to two booleans you to first compare the variable to the first boolean and then compare the variable to the second boolean. So while hungry != True or False should be while hungry != True or hungry != False . If you use the later, you will get the wrong answer. Do the same for all your other if and while statements. So your code should be:

hungry = None
while hungry != True or hungry == False:
    hungry = input('Hey, are you hungry?')
    if hungry == 'yes' or hungry == 'ye' or hungry == 'y' or hungry == 'yeah':
        print ('oh you hungry huh')
        hungry = True
    elif hungry == 'no' or hungry =='n' or hungry =='nah' or hungry =='nope':
        print ('no food for you then')
        hungry = False
    else:
        print ('its a simple yes or no question pls')

Edit: Others are suggesting membership statements which work too. However, since it looks like you're a beginner from the code you have written, I think my explanation will be easier for you to understand.

Answer 6

Your code didn't work because you're using statements in the wrong way, such as hungry != True or False , here's a working version of your code:

hungry = None
while hungry not in (True, False): # Check if hungry is not True or False
    hungry = input('Hey, are you hungry?')
    if hungry in ('yes', 'ye', 'y', 'yeah'):
        print ('oh you hungry huh')
        hungry = True
    elif hungry in ('no', 'n', 'nah', 'nope'):
        print ('no food for you then')
        hungry = False
    else:
        print ('its a simple yes or no question pls')