help with login authen

void authUser()        // Function that prompts for user to login and matches input with userdatabase.txt
{
    string accountID = "";        // initialize temp accountID to null
    string password = "";        // initialize temp password to null
    int invalidCount = 0;

    char c = ' ';

    bool validUser = false;
    bool failedLogin = false;

    while (validUser != true) // to check for invalid login
    {
        system("clear");
        using std :: cout;
        using std :: endl;
        void Encrypt( char [ ] ); // prototypes of functions used in the code
        void Decrypt( char * ePtr );

        cout << logo_MainMenu << endl;
        if (failedLogin == true)                // Displays error before asking for username/password
        {
            if (invalidCount == 1)              // tests for invalid login, 1 / 3 chance used up
            {
                cout << "\E[1;32mInvalid Account ID / Password. Please try again!\E[0m" << endl;
                cout << "You have used up 1 / 3 chances to login." << endl;
                cout << "If you fail to login after 3 tries, the application will lock down and exit!" << endl;
            }
            else if (invalidCount == 2)         // tests for invalid login, 2 / 3 chance used up
            {
                cout << "\E[1;32mInvalid Account ID / Password. Please try again!\E[0m" << endl;
                cout << "You have used up 2 / 3 chances to login." << endl;
                cout << "If you fail to login after 3 tries, the application will lock down and exit!" << endl;
            }
            else                                // tests for invalid login, 3 / 3 chance used up
            {
                cout << "\E[1;32mInvalid Account ID / Password.\E[0m" << endl;
                cout << "You have used up 3 / 3 chances to login." << endl << endl;
                cout << "The application will now lock down and exit!" << endl;
                exit (0);                       // exit application
            }
        }
        cout << endl << "To login, please enter your Account ID and Password" << endl;
        cout << "(type \"exit\" to terminate the application)" << endl << endl;
        cout << "Account ID: ";
        getline (cin, accountID);

        if (accountID == "exit")                // user can exit anytime
            exit (0);
        // by typing "exit" at username or password
        if (password == "exit")
            exit (0);

        char clear[200] = {0};
        char cipher[200] = {0};  // trying to to encrypting and decrypt 
        char filename[80];
        int x,i;
        ofstream outputFile;
        outputFile.open("yxy.txt"); // the text file that my encrypted password goes into

        ifstream userDatabaseIN("userdatabase.txt", ios::in); // the text file that userdata is stored at

        cout << "Enter Password:" ;   // asking for password
        cin.getline(clear,sizeof(clear));

        x = strlen(clear);
        // Encryption
        for(i=0; i<=x-1; i++)
        {
            if (isspace(clear[i]))
            {
                cipher[i] = clear[i];
            }
            {
                cipher[i] = clear[i]+3;
            }
        }

        // Decryption
        for(i=0; i<=x-1; i++)
        {
            if (isspace(cipher[i]))
            {
                clear[i] = cipher[i];
            }
            else
            {
                clear[i] = cipher[i]-3;
            }
        }


        outputFile<<" Encrypted:" << cipher << endl;
        outputFile<<" Decrypted:" << clear << endl;    //output 
        cout<<"Encrypted and Decrypted password transfer to yxy.txt\n"; 


        return ;
    }