Problems Understanding Conditions In If Statement Python

Hello i am a beginner in python programming and I have to write a rock paper scissor game. However the only strings that should be typed in are rock, scissor or paper. if i check

Solution 1:

It's a valid expression, just doesn't do what you might think it does:

if player1 andplayer2== 'rock' or 'paper' or 'scissor':

is checking several things:

playerplayer2== 'rock''paper''scissor'

A string is convertible to bool if its non-empty. So in this case 'paper' and 'scissor' both evaluate as True. Thus, we can rewrite your condition as the following, adding parenthesis for emphasis:

if  (player1 and player2 == 'rock') orTrueorTrue:

Which is equivalent to

ifTrue:

Probably not what you want to check.

Solution 2:

Your if statement reads:

if player1 andplayer2== 'rock' or 'paper' or 'scissor':

Python allows you to omit parentheses, but this is how it is parsed:

if (player1) and (player2 == 'rock') or ('paper') or ('scissor'):

Meaning, it checks for the truthiness of player1, whether player2 is 'rock', or whether 'paper' or 'scissor' are truthy.

In Python, a non-empty string is always truthy meaning 'paper' or 'scissor' will always be True.

What you actually want is something like

if player1 in('rock', 'paper', 'scissor') and player2 in('rock', 'paper', 'scissor')