Why Doesn't This "is Not" If Statement Work?

This is my code, if diff != '1' or diff != '2' or diff != '3': print('You need to pick either 1, 2 or 3\n') For some reason, the outcome is, Pick a difficulty: 1) Ea

Solution 1:

To apply the logic of "not any" you would want to check if it is any of the valid results then invert. (NOR)

if not (diff == "1" or diff == "2" or diff == "3"):

Or applying DeMorgan's theorem this would be equivelent to "not equal to 1 AND not equal to 2 AND not equal to 3"

if diff != "1" and diff != "2" and diff != "3":

of course python also has the in and not in operator which makes this much cleaner:

if diff not in ("1", "2", "3"):

Solution 2:

You need to use and instead of or. If you input 1, then diff != "1" returns True.

Your code should look like this:

if diff != "1" and diff != "2" and diff != "3":
            print("You need to pick either 1, 2 or 3\n")