Python while loop boolean only showing as 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')

Type in 'True or False' at the REPL and see what you get.

Marcin
– Marcin

2018-03-12 02:03:01 +00:00
Commented Mar 12, 2018 at 2:03 — Marcin
– Marcin, Commented Mar 12, 2018 at 2:03

Marcin · Accepted Answer · 2018-03-12 02:37:10Z

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)

Pdubbs · Accepted Answer · 2018-03-12 02:01:06Z

0

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')

answered Mar 12, 2018 at 2:01

Pdubbs

1,9972 gold badges13 silver badges20 bronze badges

3 Comments

Marcin Over a year ago

I think there's an opportunity here for some education. the hungry variable goes from None, to a boolean, to a string, to a boolean, etc. It's workable in this little scenario, but I don't think the OP will learn much out of this approach. I've added an answer below to explain.

Pdubbs Over a year ago

Good point. My focus was to get what they had written working, but it's definitely bad style to keep changing the type of hungry.

Marcin Over a year ago

But impressive on how you were able to keep to the original style ;-p

Joseph Sible-Reinstate Monica · Accepted Answer · 2018-03-12 01:56:05Z

0

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.

answered Mar 12, 2018 at 1:56

Joseph Sible-Reinstate Monica

49k7 gold badges55 silver badges118 bronze badges

1 Comment

kiyah Over a year ago

Or you can also use if x in (a, b, c)

accdias · Accepted Answer · 2018-03-12 02:01:39Z

0

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')

answered Mar 12, 2018 at 2:01

accdias

5,3523 gold badges24 silver badges33 bronze badges

Comments

user8177336 · Accepted Answer · 2018-03-12 02:02:11Z

0

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.

answered Mar 12, 2018 at 2:02

user8177336

3 Comments

Nathan Byrne Over a year ago

You're right, I haven't covered membership statements, and your code is familiar with what I have covered so far. However I found Pdubbs the most useful as it looks cleaner with less code and I didn't know about the in statements beforehand. Thanks for the help

user8177336 Over a year ago

@NathanByrne Yeah, I understand. No problem. It was my pleasure.

Marcin Over a year ago

Note, you can write hungry != True or False, but python short circuit evaluation on or will return True, so the comparison is always hungry != True

kiyah · Accepted Answer · 2018-03-12 02:03:11Z

0

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')

answered Mar 12, 2018 at 2:03

kiyah

1,5262 gold badges21 silver badges31 bronze badges

Collectives™ on Stack Overflow

Python while loop boolean only showing as True

6 Answers 6

Comments

3 Comments

1 Comment

Comments

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

Comments

3 Comments

1 Comment

Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related