How do I navigate through a Python list for each function call?

Question

I have this code as an example:

#         0   1   2   3   4
lista = ['1','2','3','4','5']

def nexxt():
    for item in range(len(lista)):
        item += 1       
        print(lista[item])

def back():
    for item in range(len(lista)):
        item -= 1
        print(lista[item])

I want to print every object on every call... Like I call Nexxt he prints 1 because 0 is gone, I call again and he prints 2 and so it goes...and with the back the opposite...I want to adapt this to a project where I can jump and return songs where the list will have the name of each . mp3 and the pygame/ mixer does the rest

This code is not useful, because it does not return correctly from 0 to 4...if someone can give me a light

Answer 1

There are many ways to do what you want and one of them is by creating an auxiliary variable to know the current index of the list, working as a pointer that marks where you left off in the list.

Within its functions nexxt and back there should be no loop for since you don’t want to go through your list every call. What you need to do is just increment or decrease the value of the auxiliary variable so that the pointer is changed at each call.

See the example below:

songs = ["Run Away (Moldova).mp3", "Real Gone.mp3", "Sun shine it.mp3", "MADKID - Rise.mp3"]
pointer = 0

def play_song():
    global pointer
    print("Playing " + songs[pointer])

def next_song():
    global pointer
    if pointer < len(songs) - 1: pointer += 1

def back_song():
    global pointer
    if pointer > 0: pointer -= 1