How to loop an array when it ends? Here are my failures...

[abeplaga]

Hi. So I'm testing how works arrays and I want a botton to show one by one the contents of the array and once it reaches the end it will restart (like A, B, C, A, B, C, A, B, C...).

With the following code I think that I have created it: I have a counter that shows the content one by one and when I get to the last content of the array it becomes 0 and therefore I return to the beginning but I do not get it, I get the error IndexError: list index out of range.

Code: Select all

define myarray = ["A", "B", "C"]
define counter = 0

screen test_array:
    imagebutton idle "button.png" action SetVariable("counter", counter + 1)

    if counter == len(myarray):
        $ counter = 0 

    text myarray[counter]

Looking and looking I do not find anything wrong in the code and I think it is quite logical but for some reason (ignorance maybe) I can not find out

1. With if counter == len(myarray) it loop and shows "A" but next appears IndexError: list index out of range
2. With if counter >= len(myarray) it loop and shows "A" but then it stagnates and stays in "A" no matter how much I press the button
3. With if counter <= len(myarray) I press the botton but only appears "A" but on the 4th botton press it appears IndexError: list index out of range

[Imperf3kt]

I don't know much about this, but you should use default for "counter" variable as it changes. define is for things that won't change.

[IrinaLazareva]

Code: Select all

default counter  = 0
define myarray = ['A', 'B', 'C']
screen test_array():
    imagebutton idle 'button.png' action If(counter<len(myarray)-1, SetVariable('counter', counter+1), SetVariable('counter', 0))
    text myarray[counter]

https://www.renpy.org/doc/html/screen_actions.html#If


In your example, the list consists of three elements. And the index for them is measured from zero to two.
I.e. max index is not equal to the number of elements, so such comparison causes the 'list index out of range' exception.

[Human Bolt Diary]

What you want is a modulo: https://en.wikipedia.org/wiki/Modulo_operation

Code: Select all

textbutton "Foo" action SetVariable("counter", (counter + 1) % len(myarray))

The remainder can never be greater than the length of your list

ie:

1 % 4 = 1
2 % 4 = 2
3 % 4 = 3
4 % 4 = 0
5 % 4 = 1