Tictactoe.py

def switch_turn(turn):
    if turn == "X":
        return "O"
    else:
        return "X"

def printboard(board):
    print()
    print(board[1] + " | " + board[2] + " | " +board[3])
    print("- + - + -")
    print(board[4] + " | " + board[5] + " | " +board[6])
    print("- + - + -")
    print(board[7] + " | " + board[8] + " | " +board[9])
    print()

def get_input(turn, board):
    while True:
        print(turn + "'s turn")
        position = input("Enter the position you want to play: ")

        if not position.isdigit(): # what if user enters something that is not a number?
            print("Please enter a number. ")
        elif not 1 <= int(position) <= 9:
            print("Enter a number in the valid range.")
        elif not board[int(position)].isdigit():
            print("Position already taken, please try another position.")
        else:

            return int(position)

def checkwin(board):
    if board[1] == board[2] == board[3]:
        return True, board[3]
    elif board[4] == board[5] == board[6]:
        return True, board[6]
    elif board[7] == board[8] == board[9]:
        return True, board[9]
    elif board[1] == board[4] == board[7]:
        return True, board[7]
    elif board[2] == board[5] == board[8]:
        return True, board[5]
    elif board[3] == board[6] == board[9]:
        return True, board[9]
    elif board[1] == board[5] == board[9]:
        return True, board[9]
    elif board[3] == board[5] == board[7]:
        return True, board[7]
    else:
        return False, None



def main():
    turn = "X"
    board = ["0", "1","2", "3","4", "5","6", "7","8", "9"]
    printboard(board)
    game_over = False
    count = 0
    while not game_over and count < 9:
        position = get_input(turn, board)
        count += 1
        board[position] = turn
        printboard(board)
        game_over, winner = checkwin(board)
        turn = switch_turn(turn)

    print(winner, "won the game")

main()