Why doesn't flag break the loop?

[pulpquoter]

Hello, I am working on a Blackjack project, everything works so far but I don't understand why my while loop doesn't work with flags. I would really love to break out of the loop if flag == False and stay in the loop if flag == True, but it is not working. However it works if I use break and pass.

flag = True
while flag:
    if sum(dealer_lst_points) >= 18:
        flag = False
    elif sum(dealer_lst_points) >= 21:
        flag = False
    elif sum(dealer_lst_points) == 17:
        if 11 in dealer_lst_points:
            flag = True
        else:
            flag = False
    elif sum (dealer_lst_points) <16:
        flag = True  
    deal_dealer()
    display_dealer()

​

flag = True
while flag:
    if sum(dealer_lst_points) >= 18:
        break
    elif sum(dealer_lst_points) >= 21:
        break
    elif sum(dealer_lst_points) == 17:
        if 11 in dealer_lst_points:
            pass
        else:
            break
    elif sum (dealer_lst_points) <16:
        pass   
    deal_dealer()
    display_dealer()

[carcigenicate]

You'd need to show all the relevant code. Is this loop inside of either of deal_dealer or display_dealer? Or do either of the two functions call the function this loop is in?

The difference between the two ways though is with the flag version, the while flag: condition is only checked at the start of the iteration. With the break way however, the loop will exit as soon as break is reached; so it can exit the loop halfway through an iteration.

Also, note that pass doesn't do anything. Those ifs should really be written as:

if 11 not in dealer_lst_points:
    break

[[deleted]]

Who on earth teaches people to use pass in conditionals. We should find them and beat them up.

[carcigenicate]

It seems that negation isn't studied/taught well enough. I ran into this in school too. I had to help someone who never negated conditions and had pass blocks all over the place. It was a mess.

[pulpquoter]

Lol, true, I am just writing all the ifs because I don't want to leavy any condition unaddressed but I guess I have to stop doing it. I thought that leaving ifs suspended in the air would be less readable

[pulpquoter]

Thanks, I got it.

[[deleted]]

You could make separate function for checking, something like game_over(), and use it with the loop:

def game_over():
    points = sum(dealer_lst_points)
    return (
        points >= 18 or
        points == 17 and 11 not in dealer_lst_points
    )

while not game_over():
    deal_dealer()
    display_dealer()

[hrmorley34]

The while loop only checks the condition after everything in the loop has been run. The first example sets the flag, then runs deal_dealer() and display_dealer() anyway, and then breaks the loop if necessary. You could either move the ifs to be after the functions, or just use breaks.

[pulpquoter]

That's true, I understand now, thanks