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Abstract confusion of class inheritance

I have class D inheriting from abstract class C and writing to a console related message. I expect to see "D" in the console window, but it writes "B". I think the virtual keyword in class C is breaking the rule. I didn't understand why. Can someone please explain?

  class Program
{
    static void Main(string[] args)
    {
        A obj = new D();
        obj.Write();
        Console.Read();
    }
}

public abstract class A
{
    public virtual void Write()
    {
        Console.WriteLine("A");
    }
}

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

public abstract class C : B
{
    public virtual void Write()
    {
        Console.WriteLine("C");
    }
}

public class D : C
{
    public override void Write()
    {
        Console.WriteLine("D");
    }
}
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2 answers


Your compiler already works pretty well here if you listen to it:

warning CS0114:

'C.Write()' hides inherited member 'B.Write()'.


To have the current member override this implementation, add the override keyword .

If not, add a new keyword .

The fact that you used virtual

instead override

in C will result new

in the default behavior for that method, breaking the inheritance chain.

+2


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The problem is C

not overriding a function from a class A

. The compiler gives you a keyword warning new

. If you also use override

in a class C

, it works as you'd expect.



Or, if you replace A obj = new D();

with D obj = new D();

, you get the same result.

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