CODEWITHSUNDEEP
c++classinstance
Shibli
Shibli

Reputation: 6149

A class which does not need an instance

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?

Upvotes: 2

Views: 327

Answers (6)

Theolodis
Theolodis

Reputation: 5102

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...

Upvotes: 6

user3415329
user3415329

Reputation: 21

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".

Upvotes: 2

H&#233;ctor Asencio L
H&#233;ctor Asencio L

Reputation: 141

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

Upvotes: 0

Michał Banasiak
Michał Banasiak

Reputation: 960

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

Upvotes: 0

Sargis Koshkaryan
Sargis Koshkaryan

Reputation: 1030

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

Upvotes: 1

Komi Golov
Komi Golov

Reputation: 3471

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.

Upvotes: 2

Related Questions