if variable != "string" or variable != "string_2" always evaluates the same. Never goes to else

Question

My understanding of the following code is that if user_input does not equal "up" or "down", it should keep looping. But if it does equal "up" or "down", then it changes valid_move to True and stops looping. But no matter what the user input is, it always prints ("Invalid entry") and never gets out of the while loop.

valid_move = False

while not valid_move:
    user_input = input("enter up or down")
        if user_input != "up" or user_input != "down"):
            print("invalid entry")

        else:
            valid_move = True
            print(user_input)

Why is that?

`if user_input not in ('up', 'down')`… – deceze May 14 '20 at 12:03 — deceze, May 14 '20 at 12:03

score 1 · Answer 1 · answered May 14 '20 at 11:57

1

The mistake is your condition, instead of:

if user_input != "up" or user_input != "down")

Use:

if user_input != "up" and user_input != "down")

answered May 14 '20 at 11:57

RMPR

3,368
4
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score 1 · Answer 2 · answered May 14 '20 at 11:58

1

Use "and" instead of "or" in your if statement as said by

answered May 14 '20 at 11:58

Campbell Skene

61
1
3

if variable != "string" or variable != "string_2" always evaluates the same. Never goes to else

2 Answers2