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Python

Jordan Amanda
Jordan Amanda
2,275 Points
Posted by Jordan Amanda
Jordan Amanda
2,275 Points

Why/How does the list (guesses) "reset" after each run of game()?

So we create the variable list guesses and set it as an empty list. When we run game() we are adding the user's incorrect guesses to the list and we run a while loop until the list contains 5 or more incorrect guesses. This much I understand, but I'm stuck on why the list becomes empty again after each run of game(). Is this because changes to variables do not stay when they're changed in a loop? 

def game():
    # generate a random number between 1-10
    secret_num = random.randint(1, 10)
    guesses = []

    while len(guesses) < 5:
        try:
            # get a number guess from player
            guess = int(input("Guess a number between 1 and 10: "))

        except ValueError:
            print("{} isn't a number!".format(guess))

        else:           
            # compare guess to secret number
            if guess == secret_num:
                print("you got it! My number was {}".format(secret_num))
                break
            elif guess < secret_num:
                print("My number is higher than {}".format(guess))
            else:
                print("My number is lower than {}".format(guess))
            guesses.append(guess)       
    else:
        print("You didn't get it! My number was {}".format(secret_num))

    play_again = input("Do you want to play again? Y/n ")
    if play_again.lower() != 'n':
        game()
    else: print("Bye!")

game()

With my limited knowledge, I expected guesses to contain the guesses from previous runs of game() since we never explicitly "emptied" it, but this is not the case. Any help is appreciated.

1 Answer

osd
osd
3,246 Points

guesses will keep your previous guesses but in a different function stack. Essentially you calling the function game() inside of itself just starts a new stack of this function, or in other words starting it over. Which will then start the list guesses as an empty list. This is a new variable guesses that is unrelated to the previous.

Just to note, that since the function game() calls itself inside of the function, the stack will keep building on top of itself until you quit the game. Looking like this:

[initial game() call] [play again game() call][play again game() call]... until the you quit

So in each of these stacks there is a variable named guesses that has its own memory location and will hold your user input guesses for each game() call, but each will only hold your guesses from each individual game.

Hope this helps.