A class which does not need an instance

Question

Is it possible to make a class which does not need to be instantiated? In other words, is it possible to use functions of that class without having an instance of it?

Answer 1

You could make all member functions and variables static, but then one starts to wonder why it should be a class, and not a namespace.

There is a good reason, though: you may want to use a class template like this. C++14 will add variable templates, which make the same possible without a class. A class also allows access control; you can fake this for the non-template case with anonymous namespaces, but a class may be more natural.

Answer 2

You can use static functions, those are bound to the Class, not an instance.

class Test{
    static void 
    doSomething()
    {
        std::cout << "something" << std::endl;
    }
}

int
main(int argc, char** argv)
{
    Test::doSomething(); //prints "something" without instance of Test
}

Otherwise you could build a Singleton, in which case the class itself would hold the instance, but I am not sure if this is what you wanted to know...

Answer 3

A static method can be called without creating an instance of the class.

class CMyClass
{
    public:
    static void Method1()
    {
        printf("Method1\n");
    }
};

CMyClass::Method1();    // Prints "Method1".

Answer 4

Yes, it is possible. If you want to use of class without having instance of it, you must use static functions.

Answer 5

You can also create private constructor of such class with static methods to prevent from creating any instances

Answer 6

For that you should use the static modifier. See documentation here: http://msdn.microsoft.com/en-us/library/s1sb61xd.aspx