Static Data Members - c++

Question

Please have a look at the following code
GameObject.h
#pragma once
class GameObject
{
public:
GameObject(int);
~GameObject(void);
int id;
private:
GameObject(void);
};
GameObject.cpp
#include "GameObject.h"
#include <iostream>
using namespace std;
static int counter = 0;
GameObject::GameObject(void)
{
}
GameObject::GameObject(int i)
{
counter++;
id = i;
}
GameObject::~GameObject(void)
{
}
Main.cpp
#include <iostream>
#include "GameObject.h"
using namespace std;
int main()
{
//GameObject obj1;
//cout << obj1.id << endl;
GameObject obj2(45);
cout << obj2.id << endl;;
// cout << obj2.counter << endl;
GameObject obj3(45);
GameObject obj4(45);
GameObject obj5(45);
//Cannot get Static value here
//cout << "Number of Objects: " << GameObject
//
system("pause");
return 0;
}
Here, I am trying to record how many instances have been created. I know it can be done by a static data member, but I can't access it withing the Main method! Please help!
PS:
I am seeeking for a direct access, without a getter method

Answer 1

Your static variable, counter cannot be accessed because it isn't a member of GameObject. If you want to access the counter, you'll need to do something like this:
GameObject.h
#pragma once
class GameObject
{
public:
...
static int GetCounter();
...
};
GameObject.cpp
int GameObject::GetCounter()
{
return counter;
}
Then you can access the variable like:
cout << "Number of Objects: " << GameObject::GetCounter();
Of course, there are other ways of accessing a static variable, such as making the counter variable a static member of your GameObject class (which I would recommend).

Answer 2

In your code, counter is not a static member of your class, but just a good old global variable. You can read up on how to declare static member variables anywhere on the net, but here are some snippets:
GameObject.h
#pragma once
class GameObject
{
public:
GameObject(void);
GameObject(int);
~GameObject(void);
private:
int id;
// static members
public:
static int counter; // <<<<<<<<<<< declaration
};
ameObject.cpp
#include "GameObject.h"
int GameObject::counter = 0; // <<<<<<<<<<< instantiation
GameObject::GameObject(void)
{
counter++;
}
GameObject::GameObject(int i)
{
counter++;
id = i;
}
GameObject::~GameObject(void)
{
}
Main.cpp
#include <iostream>
#include "GameObject.h"
using namespace std;
int main()
{
GameObject obj2(45);
cout << "version one: " << obj2.counter << endl;
// second version:
cout << "version two: " << GameObject::counter << endl;
system("pause");
return 0;
}
Afaik accessing static members on an instance of that class should work fine, but it gives the wrong impression, you should prefer version two.

Answer 3

Never mind, I did it with a getter method. Closing thread