Does a variable itself consume memory?

Question

When we declare a variable, does the variable itself consume memory?

 class IHaveNothing
{
}

class IHaveNullFields
{
    string @string = null;
    StringBuilder @StringBuilder = null;
}

class Program
{      
    static void Main(string[] args)
    {
        IHaveNothing nothing = new IHaveNothing();
        IHaveNullFields nullFields = new IHaveNullFields();
    }
}

Does the instance nullFields consume more memories than the instance nothing ?

EDIT: How about null local variables as opposed to class' null fields, do they consume memory too?

Answer 1

Yes, they consume the pointer size of the machine (at least).

Answer 2

A variable is defined as a storage location. So the question is: does a storage location consume memory?

When you say it that way it sounds obvious that the answer is yes. What else would a storage location do other than consume memory?

It's not as simple as that. A local variable can consume no memory at all; a local variable might be enregistered by the jitter. In that case it would consume neither stack nor heap memory.

Why do you care? The way that the CLR manages memory to make storage locations for variables is an implementation detail. Unless you're writing unsafe code, you don't have to worry about it.