How to write OR expression correctly

Asked Sep 10 '18 at 07:41

Active Sep 10 '18 at 08:07

Viewed 32 times

I have a very simple program, where it just check the user's input and ask eventually for a correct input.

player1 = input('Scissors (S), Rock (R), Paper (P) ?:')

while player1 is not 'S' or 'R' or 'P':
 player1 = input('Invalid Input, please choose correctly! /n Scissors (S), Rock (R), Paper (P) ?:')

If players1 is 'S' or 'R' or 'P' then it still asks for a correct input. I am not sure what I am missing. Excuse me if this might sound very trivial.

Edit:

writing it this way still does not recognize a correct input

   while player1 is not 'S' or player1 is not 'R' or player1 is not 'P':
   while player1 in {'S', 'R', 'P'}:

this way is just recognize 'S' as correct, if a type 'R' is still wrong

while player1 != 'S' and 'R' and 'P':

Correct:

while player1 != 'S' and player1 != 'R' and player1 != 'P':

edited Sep 10 '18 at 08:07

asked Sep 10 '18 at 07:41

xava

Do not use `is` for equality checks, but `==`, and the logical connector should probably be `and` for your code to make some sense. – user2390182 Sep 10 '18 at 07:48
Your new issue is also a duplicate (can't find it now). TL;DR: Use `and`, not `or`. – melpomene Sep 10 '18 at 07:49
Why and? Just one input value should be entered and not all three of them – xava Sep 10 '18 at 07:50
https://stackoverflow.com/questions/1504717/why-does-comparing-strings-in-python-using-either-or-is-sometimes-produce is one of the dupes. – melpomene Sep 10 '18 at 07:50
@xava Because you're doing an inequality check. Every input is either not `S` or not `R` (i.e. the condition is always true). – melpomene Sep 10 '18 at 07:52
1

`x != 'S' or x != 'R'` is always true. You won't find a vaue for `x` for which it isn't – user2390182 Sep 10 '18 at 07:52
I used now != and the logical connector 'and' but now just the first value is correctly recognized – xava Sep 10 '18 at 07:56
1

Now we're back to the original issue. – melpomene Sep 10 '18 at 07:58
I have corrected it now, thank you for bearing with me – xava Sep 10 '18 at 08:09

How to write OR expression correctly

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