Play with inheritance [duplicate]

Question

I was just tying to understand what is happening when I write a=c; when I checked type of "a" it is showing up as class "C". Now my question here is if "a" is pointing to "c" then why it is not behaving like pointer "c".

 class Program
    {
        static void Main(string[] args)
        {
            C c = new C();
            A a = new A();
            Console.WriteLine(a.GetType());
            a = c;
            Console.WriteLine(a.GetType());
            a.Show();
            c.Show();
            Console.ReadLine();
        }
    }
class A
{
    public virtual void Show()
    {
        Console.WriteLine("A.Show()");
    }
}

class B : A
{
    public override void Show()
    {
        Console.WriteLine("B.Show()");
    }
}

class C : B
{
    public new void Show()
    {
        Console.WriteLine("C.Show()");
    }
}

Output:

Answer 1

It's because you're using the new keyword.

The new keyword simply hides the underlying method and replaces it with a new method. When you cast the object to A (or even B), you're using the hidden method in B, not the new method in C.

You can read more about it in the docs here and here.

Answer 2

Actually, it is 'a pointer "c"'. But as @John said, the new keyword is the issue here.

The result would be what you expected for if you didn't set a type to a variable.

For example:

public static void Main()
{
    C c = new C();
    object a = c;
    Console.WriteLine(a.GetType()); // It still is of `C` type instead of object as you've set
    ((A)a).Show(); // Prints out "C.Show" 
    c.Show(); // Prints out "C.Show"
    Console.ReadLine();
}

Once you're expecting an 'A' kind of behavior to the Show method it acts as an A known method. As C have a NEW behavior it's unknown to A (or B), even having an old Show (that's the inherited from B) for ascendents compatibility.

In resume: The Show method of C class is a new one that 'coincidentally' have the same name. But it's known by the C class (and it's children) only.