Objects using other objects

[Mr Bojangles]

I'm a little new to this, So I might accidentally call something by the wrong name, so bare with me for a moment.

I am making a Black Jack game, so far I have 3 class's, the deck, the dealer, and the player. I create the deck object in main (deck1), but if I make a statement in a dealer function such as

Deck1.GetCard();

I get a compiler error. It says Deck1 was not declared in this scope. My work around is returning control back to main, getting a card (as an integer) then feeding that integer as a dealer function parameter.

My question: How can I have a class use a function from a different class?

In code example

#include <iostream>
using namespace std;

class NeedsADog
{
    public:
        void GetRandomDog(); // Attempts to use a Dog function
};

class Dog
{
    public:
        void ThingsDogsDo();
};

void NeedsADog::GetRandomDog()
{
    WoofieMcWoofienstein.ThingsDogsDo(); // Uses a specific object declared in main
}                                     // Error: WoofieMcWoofienstein was not declared in this scope

void Dog::ThingsDogsDo()
{
    cout << "Woof";
}

int main()
{
    NeedsADog LittleBoy; //cuz every little boy should have a dog
    Dog WoofieMcWoofienstein; // Great name for a dog, if I do say so myself
    LittleBoy.GetRandomDog; // The little boy is trying to get a dog, any dog will do
    return 0;           // Error: statement cannot resolve address of overloaded function
}

Compiling that chunk of code gives 2 errors, I commented on the line that the errors point to, and gave the error it stated. They are found on lines 19 and 31

[firedraco]

As you found out, you can't do it like that. It sounds like you might have some sort of issue with your design.

Shouldn't the dealer have a deck object inside of them (because it's the dealer's deck, not just any deck)?

[Mr Bojangles]

Thank you, so does that mean I would have to make the deck a subclass of the dealer? I was hoping to make the deck its own class, so I could just copy paste it easier to other card game related projects.

[firedraco]

I'm not sure what you mean by 'subclass'. What I meant was something like this:

#include "deck.hpp" //or wherever deck is

class Dealer {
private:
    Deck deck;
public:
    //functions to modify deck/deal/etc
};

[Mr Bojangles]

To be honest, I really don't know what subclass is either, I read it in a book.

Thank you for your help.

[Mr Bojangles]

I'm terrible with headers, couldn't get it to work through headers (most likely just because I'm so terrible at them)

I figured it out, passing through by reference and rearranging the way I declared my prototypes. Also, the line 31 error was because I forgot to include the (). Anyways, for anyone who also comes across this problem, the updated code with comments on what I changed to get it to work.

#include <iostream>
using namespace std;

class Dog
{
    public:
        void ThingsDogsDo();
};

class NeedsADog
{
    public:
        void GetRandomDog(Dog &rDog); // Attempts to use a Dog function, recieves a reference to the dog object passed through from line 32
};                                    // The dog class needs to be declared first, so that GetRandomDog can have a Dog object defined as a parameter



void NeedsADog::GetRandomDog(Dog &rDog)
{
    rDog.ThingsDogsDo(); // Uses a specific object declared in main
}

void Dog::ThingsDogsDo()
{
    cout << "Woof";
}

int main()
{
    NeedsADog LittleBoy; //cuz every little boy should have a dog
    Dog WoofieMcWoofienstein; // Great name for a dog, if I do say so myself
    LittleBoy.GetRandomDog(WoofieMcWoofienstein); // I pass through the object to NeedsADog on line 13
    return 0;
}

[hanst99]

Oh, and even though it's not directly related to the topic: A 'subclass' is a class which inherits from another class. It's part of object oriented design.

To give an example:
Cars and Planes are different. If you wanted to create car objects, you would write a car class, if you wanted to create plane objects, you would create a plane class. However, both car and plane have similar properties, like a maximum speed, the ability to move etc. Here you could write a superclass "Vehicle" that contains all properties and methods all vehicles have in common. Car and Plane would be subclasses of that class. (So basically, subclass and superclass are relative words: You normally don't say "this class is a superclass", but rather "this class is the superclass of that class" or "this class is a subclass of that class".