static void Main(string[] args)
    {
        int shutdown = 0;
        string command;

        Console.WriteLine("Initialising Empty Linked List...");
        //initialise the linked list
        linkedList pList = new linkedList();
        //get user input on what they want to do
        print_help();
        while (shutdown != (int)return_code.SHUTDOWN)
        {
            Console.Write("#Linked_List Controller > ");
            //get user input
            command = Console.ReadLine();
            //see what the user wants to do
            switch(command)
            {
                case "p":
                case "P":
                    //print out the contents of the linked list
                    pList.print_list();
                    break;
                case "i":
                case "I":
                    create_node(pList);
                    break;
                case "d":
                case "D":
                    delete_node(pList);
                    break;
                case "s":
                case "S":
                    search_node(pList);
                    break;
                case "q":
                case "Q":
                    shutdown = (int)return_code.SHUTDOWN;
                    break;
                case "h":
                case "H":
                    print_help();
                    break;
                default:
                    Console.WriteLine("Invalid input, type 'h' for help.");
                    break;
            }
        }
    }