//Sign in Page public bool SignInPage() { //loop until valid input or user choose 'back' while (true) { // ask for username Console.WriteLine("Please enter your Username:"******"Please enter your password: or enter \"Back\" to main menu"); string password = Console.ReadLine(); if (password.ToLower().Equals("back")) { return(false); } //check if the account exists //if exist, the AccountMatch method would also save information of account to CurrentAccount Class if (!BL.AccountMatch(username, password)) { Console.WriteLine("Username or Passward doesn't match. Please try again.\n"); } else { //after sign in,open or create json file for saving bank account information if (new BankAccountBL().FetchInfo()) { break; } } }//end of loop return(true); }