Variable does not update in while loop

Question

Why doesn't current_score update in the while loop? First time posting, couldn't find the answer online. I guess it's a scoping issue halp

def main():
    player_1 = input("Player one: ")
    player_1_score = 0
    player_2 = input("Player two: ")
    player_2_score = 0
    num_sets = int(input("Points for a win: "))
    current_score = "%s (%i : %i) %s" % (player_1, player_1_score, player_2_score, player_2)

    while player_1_score < num_sets > player_2_score:
        round = int(input("Who won this round? (type 1 for player one; type 2 for player two"))
        if round == 1:
            player_1_score += 1
        else:
            player_2_score += 1

    print(current_score)
pass

if __name__ == '__main__':
    main()

Where do you instruct it to update. Note that string formatting like ...%... is evaluated once... — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Mar 23, 2017 at 19:40

ForceBru · Accepted Answer · 2017-03-23 19:42:38Z

1

Try this:

current_score = "%s (%i : %i) %s"

while something:
    # do the update
    print(current_score % (player_1, player_1_score, player_2_score, player_2))

Here current_score is just a string containing the format specifiers. All the magic happens when you apply that format_string % (data) syntax to it. Then you get a new string that'll hold the formatted output.

answered Mar 23, 2017 at 19:42

ForceBru

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2 Comments

qutija Over a year ago

That's pretty smart. So does that mean that using '%' just stores current values in a string variable? And when i reuse that variable it just gives me the string not the "%s (%i : %i) %s" % (player_1, player_1_score, player_2_score, player_2)

ForceBru Over a year ago

@qutija, pretty much: the %s and %i themselves are merely format specifiers (i.e. just characters).

ramden · Accepted Answer · 2017-03-23 19:44:37Z

You have to reinitialize current score with the new values after the new values are set in the loop before printing out:

def main():
player_1 = input("Player one: ")
player_1_score = 0
player_2 = input("Player two: ")
player_2_score = 0
num_sets = int(input("Points for a win: "))
current_score = "%s (%i : %i) %s" % (player_1, player_1_score, player_2_score, player_2)

while player_1_score < num_sets > player_2_score:
    round = int(input("Who won this round? (type 1 for player one; type 2 for player two"))
    if round == 1:
        player_1_score += 1
    else:
        player_2_score += 1

    current_score = "%s (%i : %i) %s" % (player_1, player_1_score, player_2_score, player_2)
    print(current_score)
pass

if __name__ == '__main__':
    main()

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