NameError: variable is not defined

Question

Need some help. I created an empty list to append input of names. However, I keep getting an error "NameError: name 'players' is not defined. It works if I defined players = [] as a global variable but not as a main function. Fyi, I'm not allowed to use a global variable.

def existingPlayers(name):
    '''
    Check if player name already exists
    '''
    for player in players:
        if player[0].lower() == name.lower():
            return True
    return False

def getPlayerNames():
    '''
    Get the names of the players. Check if the number of players and 
    player names are valid
    '''
    while True:
        name = input("Enter player name or <ENTER> to exit (min 2, max 4 players):")
        if len(name) == 0:
            if len(players) < 2:
                print(f"Minimum 2 players. Currently, {len(players)} player")
                continue
            else:
                break
        if existingPlayers(name):
            print("Repeated name. Choose another name")
            continue
        players.append([name])
        if len(players) == 4:
            break
def main():
    players = []
    getPlayerNames()
main()

Answer 1

Is this what you want?

def existingPlayers(name, players):
    '''
    Check if player name already exists
    '''
    for player in players:
        if player[0].lower() == name.lower():
            return True
    return False

def getPlayerNames(players):
    '''
    Get the names of the players. Check if the number of players and 
    player names are valid
    '''
    while True:
        name = input("Enter player name or <ENTER> to exit (min 2, max 4 players):")
        if len(name) == 0:
            if len(players) < 2:
                print(f"Minimum 2 players. Currently, {len(players)} player")
                continue
            else:
                break
        if existingPlayers(name, players):
            print("Repeated name. Choose another name")
            continue
        players.append([name])
        if len(players) == 4:
            break
def main():
    players = []
    getPlayerNames(players)
main()