Question

I know what “boxing” is:

object myBox = 5;

Now I wish to increase my knowledge. Is a special type created for this boxing operation? Or is System.Object used? How does .NET handle boxing?

Answer 1

There is no special type; a boxed value type is an implementation detail of the runtime. But the easiest way to understand it is to imagine that there is a special type:

class Box<T> where T : struct
{
    T value;
}

Where the type Box<T> also implements all the methods, interfaces, and so on, of T, for whatever T happens to be. So, for example, you could imagine that Box<int> has a method ToString which simply calls int.ToString on the value, and returns the result.

Boxing is simply a mechanism for getting a reference to something that is not of reference type. You just make a box around the thing and get a reference to the box.