While loop running even after condition is False

Question

I want the user to input either 1, 2 or 3. But when I test it and enter 1,2 or 3 it still runs even though the condition is False. I keep changing the condition from and's and or's but I can't seem to solve it. Any help would be greatly appreciated.

def get_input():
    user_input = input("Enter a number 1,2 or 3:  ")

    while  (user_input != 1) and (user_input != 2) and (user_input != 3) :
        print('Invaild input!')
        user_input = input("Enter a number 1,2 or 3 : ")

Your assumption is wrong. The program is running as it has been told to do. Thus the expression is not false. — user2864740, Oct 04 '15 at 01:59
Thanks Jonathan, but how to deal with the user entering a string or a number that isnt 1 2 or 3 — user1995933, Oct 04 '15 at 02:02
Possible duplicate of [Python using \`!=\`, \`or\` and \`while\`](http://stackoverflow.com/questions/32835527/python-using-or-and-while) — Remi Guan, Oct 04 '15 at 02:03
You need to either test against strings or convert the input to an int. — lvc, Oct 04 '15 at 02:04
There is probably a dupe of this somewhere, but that proposed dupe definitely isnt it. — lvc, Oct 04 '15 at 02:05

score 1 · Answer 1 · answered Oct 04 '15 at 02:02

1

You are reading strings, you should either convert it, or use strings. So the condition should be

(user_input != "1") and (user_input != "2") and (user_input != "3")

answered Oct 04 '15 at 02:02

ergonaut

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score 1 · Answer 2 · answered Oct 04 '15 at 02:02

1

Because the value returned from input() is a string (enclosed by quote marks), not an integer.

ie.

"1" is not the same thing as 1

To fix it change this line.

while  (user_input != "1") and (user_input != "2") and (user_input != "3") :

answered Oct 04 '15 at 02:02

dwjohnston

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score 0 · Answer 3 · answered Jul 28 '21 at 09:28

You can try to change the input data type to integer from string or rather use "2" instead of 2 in your code

For Using It Without Changing The Data Type:

def get_input():
user_input = input("Enter a number 1,2 or 3:  ")

while  (user_input != "1") and (user_input != "2") and (user_input != "3") :
    print('Invaild input!')
    user_input = input("Enter a number 1,2 or 3 : ")

For changing data type to int:

def get_input():
user_input = int(input("Enter a number 1,2 or 3:  "))

while  (user_input != 1) and (user_input != 2) and (user_input != 3) :
    print('Invaild input!')
    user_input = int(input("Enter a number 1,2 or 3 : "))

While loop running even after condition is False

3 Answers3