How do I stop this loop in Python?

Question

This works exactly as I want it to, with the exception that I can't get it to stop when the user enters an invalid option. It's a Rock, Paper, Scissors game that not only registers the user's input but it keeps score of the current round and keeps the final score of all rounds until the game ends... which as it is right now, never happens. How do I end this game when the user inputs an invalid option? I tried using break, but it's invalid.

def rock_paper_scissors():
    playerScore = 0
    computerScore = 0

    print("")

    player = input("Choose Rock, Paper, or Scissors: ")
    player = player.lower()

    choices = ["rock", "paper", "scissors"]

    computer = random.choice(choices)


    if player == computer:
        print("I chose " + str(computer) + " and you chose " + player + ". It's a tie!")
    elif player == "rock" and computer == "scissors":
        playerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". Congratulations! You won! " + player + " beats " + str(computer) + ".")
    elif player == "paper" and computer == "rock":
        playerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". Congratulations! You won! " + player + " beats " + str(computer) + ".")
    elif player == "scissors" and computer == "paper":
        playerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". Congratulations! You won! " + player + " beats " + str(computer) + ".")
    elif computer == "rock" and player == "scissors":
        computerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". You lost! " + str(computer) + " beats " + player + ".")
    elif computer == "paper" and player == "rock":
        computerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". You lost! " + str(computer) + " beats " + player + ".")
    elif computer == "scissors" and player == "paper":
        computerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". You lost! " + str(computer) + " beats " + player + ".")
    else:
        print("Sorry, but you entered an invalid option.  The game has ended.  See below for the final score.  Thank you for playing")
        print("")
        print("Your score:", str(playerScore) + ", Computer score:", str(computerScore))

    return playerScore, computerScore

playerFinal = 0
computerFinal = 0

while True:
    player, computer = rock_paper_scissors()
    playerFinal += player
    computerFinal += computer
    print("Your score:", str(playerFinal) + ", Computer score:", computerFinal)

Prayush Dawda · Accepted Answer · 2018-10-07 20:38:18Z

This can be solved by simply adding a flag to check whether the while True loop needs to be ended. Here:

import random
def rock_paper_scissors():
    playerScore = 0
    computerScore = 0
    flag = False

    print("")

    player = input("Choose Rock, Paper, or Scissors: ")
    player = player.lower()

    choices = ["rock", "paper", "scissors"]

    computer = random.choice(choices)


    if player == computer:
        print("I chose " + str(computer) + " and you chose " + player + ". It's a tie!")
    elif player == "rock" and computer == "scissors":
        playerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". Congratulations! You won! " + player + " beats " + str(computer) + ".")
    elif player == "paper" and computer == "rock":
        playerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". Congratulations! You won! " + player + " beats " + str(computer) + ".")
    elif player == "scissors" and computer == "paper":
        playerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". Congratulations! You won! " + player + " beats " + str(computer) + ".")
    elif computer == "rock" and player == "scissors":
        computerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". You lost! " + str(computer) + " beats " + player + ".")
    elif computer == "paper" and player == "rock":
        computerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". You lost! " + str(computer) + " beats " + player + ".")
    elif computer == "scissors" and player == "paper":
        computerScore += 1
        print("I chose " + str(computer) + " and you chose " + player + ". You lost! " + str(computer) + " beats " + player + ".")
    else:
        flag = True
        print("Sorry, but you entered an invalid option.  The game has ended.  See below for the final score.  Thank you for playing")
        print("")
        print("Your score:", str(playerScore) + ", Computer score:", str(computerScore))

    return playerScore, computerScore, flag

playerFinal = 0
computerFinal = 0

while True:
    player, computer, flag = rock_paper_scissors()
    playerFinal += player
    computerFinal += computer
    print("Your score:", str(playerFinal) + ", Computer score:", computerFinal)
    if flag:
        break

That worked! Thank you very much for explaining that and showing it.

John Gordon · Accepted Answer · 2018-10-07 20:34:11Z

1

If the returned scores are both equal to zero, the player entered incorrect input and you can break the loop.

while True:
    player, computer = rock_paper_scissors()
    if player == 0 and computer == 0:
        break
    playerFinal += player
    computerFinal += computer
    print("Your score:", str(playerFinal) + ", Computer score:", computerFinal)

answered Oct 7, 2018 at 20:34

John Gordon

33.8k9 gold badges48 silver badges72 bronze badges

1 Comment

Matt Over a year ago

Thank you for your response. I tried that, but it just reset the final scores to 0. I need them to print the final score of all the rounds the user played when the game ends.

mooga · Accepted Answer · 2018-10-07 20:43:23Z

0

Just add break after the invalid choice You can let the player scroll at that time with minus

if player < 0
   playerFinal = -1 * player
   break

edited Oct 7, 2018 at 20:43

answered Oct 7, 2018 at 20:34

mooga

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1 Comment

John Gordon Over a year ago

This doesn't work because the choice is made inside the rock_paper_scissors() function, but the loop is at the main level.

mayurmadnani · Accepted Answer · 2018-10-07 20:50:04Z

0

Change your looping condition from:

while True:

to:

while True and (player+computer) != 0 :

With an invalid user choice, the score for that round will be 0 and next time the loop will not pass the condition.

answered Oct 7, 2018 at 20:50

mayurmadnani

3091 silver badge5 bronze badges

2 Comments

John Gordon Over a year ago

This is an error, because player and computer aren't defined until the loop is executed at least once.

mayurmadnani Over a year ago

Correct! You have to initialize them alongwith playerFinal and computerFinal. Assigning value of -1 should be fine so they dont add up to 0 and the loop is entered.

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