In a RPSLS game, if statement always make else be true-CodePudding

I'm building a RPSLS game and I have an error that I am running into. Regardless of what input player 1 selects, player 2 always win.

# 10 winning pairs, defined as (winner,loser)
winningPairs = [("scissors,paper"),
                ("scissors,lizard"),
                ("Spock,scissors"),
                ("Spock,rock"),
                ("lizard,Spock"),
                ("lizard,paper"),
                ("rock,lizard"),
                ("rock,scissors"),
                ("paper,rock"),
                ("paper,Spock")]

# ask players for their name
print()
namePlayerOne = input("Player 1, enter your name: ")
namePlayerTwo = input("Player 2, enter your name: ")
print()

# Options that can be selected by any user
options = ["Rock","Paper","Scissors","Lizard","Spock"]

# set two variables for keeping score
playerOneScore = 0
playerTwoScore = 0

while True:
    # asking players for their choice
    playerOneOption = input(f"{namePlayerOne} select your option (scissors, Spock, lizard, rock, paper): ").lower()
    playerTwoOption = input(f"{namePlayerTwo} select your option (scissors, Spock, lizard, rock, paper): ").lower() 
    if playerOneOption == playerTwoOption: # if both players select the same option, it's always a draw
        results = "Draw"
    elif (playerOneOption,playerTwoOption) in winningPairs: # check if the order of the input is the same as an element in the winningPairs list, if it is Player one wins (who selects first)
        results = f"{namePlayerOne} wins" # print their win
        playerOneScore  = 1 # add 1 score to their name
    else: # if the elif is not true, it means player two wins
        results = f"{namePlayerTwo} wins" # print their win
        playerTwoScore  = 1 # add 1 score to their name

    print("-"*20)
    print(f"{namePlayerOne} chose {playerOneOption}\n{namePlayerTwo} chose {playerTwoOption}") # print each player's pick
    print(results) # print results
    print()
    print(f"{namePlayerOne} score: {playerOneScore}\n{namePlayerTwo} score: {playerTwoScore}") # print player scores
    print("-"*20)

    playAgain = input("Play again? (y/n): ") # ask if players want to play again
    if playAgain.lower() != "y":
        break

Below is the output of what happens. The player selects their names and subsequently picks their options.

Player 1, enter your name: name1
Player 2, enter your name: name2

name1 select your option (scissors, Spock, lizard, rock, paper): rock
name2 select your option (scissors, Spock, lizard, rock, paper): scissors
--------------------
name1 chose rock    
name2 chose scissors
name2 wins

name1 score: 0      
name2 score: 1      
--------------------
Play again? (y/n): n

In this example, player 1 selects rock, and player 2 selects scissors, which means that player 1 should win.

CodePudding user response：

Your winning pairs must be defined as a list of tuples, which contain 2 strings:

winningPairs = [("scissors","paper"),
                ("scissors","lizard"),
                ("Spock","scissors"),
                ("Spock","rock"),
                ("lizard","Spock"),
                ("lizard","paper"),
                ("rock","lizard"),
                ("rock","scissors"),
                ("paper","rock"),
                ("paper","Spock")]

To clarify, this is because you are checking whether a tuple of two strings, player1 and player2's choices respectively, is in the list. The list now contained just strings, since a tuple of 1 element is defined as (item,). But, replace your winningPairs list with this one and it will be all good.

CodePudding user response：

Let's define the "winningPairs" as tuples (a pair of strings in beating order) and extract your crucial algorithm, the evaluation of win, into a function:

# pair (A,B) means: A beats B
def beating_tuples = [
    ("paper", "rock"),
    ("rock", "scissor"),
    # etc.
    ]


# returns a result statement
def evaluate_winner(player1_choice, player2_choice):
    if player1_choice == player2_choice:
       return "Draw"
    
    if (player1_choice, player2_choice) in beating_tuples:
        player1_score  = 1
        return f"{player1_name} wins"
    
    if (player2_choice, player1_choice) in beating_tuples:
        player2_score  = 1
        return f"{player2_name} wins"

    return f"Error: Choices of both unequal or not in beating-pairs (player2, player1): {(player2_choice, player1_choice)}"

Note: Instead of a defaulting else a final catching return indicates failure.

Further improvements could be a Player class, where each player object has common attributes as name, choice, score.