While Loop Odd Bug Python

Question

I'm a noob trying to learn Python. I made a function to allow a user to remove items from a list, by selecting them 1 at a time, then removing same from the list (basically, to choose dice to reroll in my Yahtzee game). So, I want a user to be able to remove 1 item or more from a list, and for the while loop to exit when the user decides on line 22 that they do not want to reroll any more dice. The function seems to works fine, unless the user selects 1 dice to reroll (say 6), then selects 'y' to reroll another, then selects another dice, and then select's n, which causes the while loop to incorrectly loop between lines 21 and 25 and back to 21 (requiring the user to enter n twice, rather than once to exit the loop. My code on Repl.it is here

Again, the problem only seems to occur if you choose at least 2 dice to remove.

dice1 = [1,2,3,4,5,6]

def sub_dice():
  while True:
    try:
      print 'line 6'
      subtract1 = int(raw_input('What dice do you want to reroll?'))
    except ValueError:
      print('Enter a number corresponding to the dice you want to reroll')
      continue
    if subtract1 not in dice1:
      print('You must select 1 of the dice from the table to remove')
    else:
      break

  if subtract1 in dice1:
    dice1.remove(subtract1)
    print "The remaining dice are " + str(dice1)

  while True:
    print 'line 21'
    more = raw_input("Do you want to reroll another dice, 'Y' or 'N?'")

    if more.lower() == 'n':
      print 'line 25'
      print "On that turn, you kept " + str(dice1)
      return len(dice1)
      break

    elif (more.lower() != 'y') and (more.lower() != 'n'):
      print('You must select Y or N')
      print 'line 32'

    elif more.lower() == 'y':
      print 'line 35'
      sub_dice()

sub_dice()

*You can see the problem by entering 6 for example, then y, then 5, and then 'n', at which point you will see it loops back to line 21 and again asks if you want to reroll another dice, even though you have indicated no.

I tried the change as suggested, but the problem persisted (again, it only shows up if you choose to remove at least 2 dice. Once the user enters 'n', I do not want them to again be asked if they want to reroll another dice. — Mike, Sep 17 '17 at 17:57
I updated [your repl](https://repl.it/LMo7/2). To me the problem is because you needlessly made your logic recursive, whereas what you want is to decouple your top loop from the lower one. — Jedi, Sep 17 '17 at 18:48
Jedi, thanks for taking a look at it. With your help, I got it to work exactly as intended. The error was happening due to the recursive nature of the logic, which I was able to fix when I made 2 nested functions inside of the larger one. https://repl.it/LMo7/3 — Mike, Sep 18 '17 at 21:43

score 1 · Answer 1 · answered Sep 17 '17 at 18:49

The reason for the behavior is that you are calling sub_dice() from within itself. Read about recursive functions, because I'm not sure you intended to do this.

When you type 'n' you are exiting from the nested sub_dice() call, so it just returns to the original call instead of exiting the program like you expect.

While Loop Odd Bug Python

1 Answers1