C++ Multiple Classes in ONE cpp file

Question

I'm required to work with multiple classes in one .cpp file. I'm not sure what I'm doing wrong, is there a header file I need to include?

These are the errors I'm getting:

error C3646: 'loginObject': unknown override specifier

error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

error C2065: 'loginObject': undeclared identifier

#include <iostream>
#include <string>
using namespace std;

//Declaration of Class that Allows User to Select a Menu Option
class Menu
{
private:
    int userChoice = 0; //User's Menu Selection

    //Class Objects
    Login loginObject;

public:
    void options()
    {
        //Loop of Initial Menu
        do
        {
            //Startup Menu
            cout << "\n\tMain Menu:"
                "\n\n\t1. Login"
                "\n\t2. Create Password"
                "\n\t3. Change Password"
                "\n\t4. Delete User"
                "\n\t5. Exit"
                "\n\nSelection: ";
            cin >> userChoice;
            cout << endl;

            //Switch Statement that Determines Course of Action based upon User's Choice
            switch (userChoice)
            {
            case 1:
                loginObject.login();    //Option to Login
                break;
            case 2:
                cout << "\nCreating Password...";  //Option to Create a New Password
                cout << endl;
                break;
            case 3:
                cout << "Changing Password...";  //Option to Change an Old Password
                cout << endl;
                break;
            case 4:
                cout << "Deleting User..."; //Option to Delete a User
                cout << endl;
                break;
            case 5:
                cout << "Exiting...";   //Option to Exit the Program
                cout << endl << endl;
                system("pause");
            default:
                cout << "INVALID MENU OPTION!\n";
                break;
            }

        } while (userChoice != 5); //Loop to Return to Initial Menu
    }
};

//Declaration of Class that Manages all Activities Dealing with Login
class Login
{
private:

public:
    void login()
    {
        cout << "\nLogging In...";
        cout << endl;
    }
};

//Main File
int main()
{
    //Call to Menu Class 
    Menu menuVariable;
    menuVariable.options();

    return 0;
}

Answer 1

Generally speaking, your C++ code is read from top to bottom. So you can't use the name Login before it's defined. In your case, you can just move Login to above Menu (since the former does not depend on the latter) and it'll all be fine. In general, you can write a prototype at the top of your file to indicate the shape of a class without showing its implementation. So, for Login, that would be

class Login {
public:
    void login(); // Note: No function body
};