C++ static members in class

Question

Hey Guys

Is it possible to access to access and use static members within a class without first creating a instance of that class? Ie treat the the class as some sort of dumping ground for globals

James

Answer 1

Yes:

class mytoolbox
{
public:
  static void fun1()
  {
    //
  }

  static void fun2()
  {
    //
  }
  static int number = 0;
};
...
int main()
{
  mytoolbox::fun1();
  mytoolbox::number = 3;
  ...
}

Answer 2

Yes, it's precisely what static means for class members:

struct Foo {
    static int x;
};

int Foo::x;

int main() {
    Foo::x = 123;
}

Answer 3

In short, yes.

In long, a static member can be called anywhere, you simply treat the class name as a namespace.

class Something
{
   static int a;
};

// Somewhere in the code
cout << Something::a;

Answer 4

You can also call a static method through a null pointer. The code below will work but please don't use it:)

struct Foo
{
    static int boo() { return 2; }
};

int _tmain(int argc, _TCHAR* argv[])
{
    Foo* pFoo = NULL;
    int b = pFoo->boo(); // b will now have the value 2
    return 0;
}

Answer 5

On the other hand, that's what namespace are for:

namespace toolbox
{
  void fun1();
  void fun2();
}

The only use of classes of static functions is for policy classes.