What does the name after the closing class bracket means?

Question

I\'ve encountered this code example and I remembered I\'ve seen it before and I didn\'t know what it is for and what it does? I\'ve searched on the internet but without luck.

Answer 1

} g_c;

Here g_c is declared to be an object of the class type C.

Such construct enables you to create object(s) of unnamed type as:

class  //Nameless class!
{
   //data members

}obj1, obj2;

In this example, obj1 and obj2 are declared to be objects of a class type which has not been given any name — the class is nameless! In such situation, you cannot declare objects in a conventional sense (i.e Type obj1, obj2; sense). So this construct helps you do that.

You can even derive from other named classes while being nameless (and declaring the objects of the nameless class):

class : public A, public B //Nameless class is deriving from A and B
{
   //data members

}obj1, obj2;

In short, this construct ensures that the user wouldn't be able to create more objects than intended, unless some evil programmer uses/misuses/abuses C++11 (or template) as:

decltype(obj1) obj3; //hehe!

Hope that helps!

Answer 2

You declare variables using the format type variable_name;. For example:

A x;

Where A may be the name of a class.

But instead of using a pre-existing class type, you can also define the class at the same time as you declare a variable of the new class's type:

class { ... } x;

or define the class and give it a name:

class A { ... } x;

In C++ it is common to just define the class and give it a name, but leave off the variable:

class A { ... };

but you don't have to leave off the variable.

Answer 3

It's shorthand for:

class C
{
    ....
};

C g_c;

Answer 4

That's just a way of creating objects of that type of Class. Structs mostly use them to initialize new variables.