C# Potential Interview Question…Too hard? [closed]

Answer 1

Console.WriteLine( "B::Foo");

Because it will cast automatictly and use the first without going further in the inheritance.

I do not think it's a good interview question but it can be funny to try to solve without compiling the code.

Answer 2

Try a similar sample given below:

class Program
{
    class P
    {}
    class Q : P
    {}

    class A 
    { 
        public void Fee(Q q)
        {
            Console.WriteLine("A::Fee");
        }
    }

    class B : A 
    {   
        public void Fee(P p)
        {
            Console.WriteLine("B::Fee");
        }
    }

    static void Main(string[] args) 
    { 
        B b = new B();   
        /* which Fee is chosen? */  

        b.Fee(new Q());
        Console.ReadKey();
    }
}

The compiler seems to prefer linking the "b.Fee()" call to an available method of the type rather than an inherited method (method of a base type) if the parameter can be implicitly cast to match any such method. I.e. implicit casting of the parameter takes precedence over base class method linking.

Though honestly I find the opposite as more intuitive, because for me an inherited method is just as good as a directly introduced method.

Answer 3

I really wouldn't use this as an interview question. I know the answer and the reasoning behind it, but something like this should come up so rarely that it shouldn't be a problem. Knowing the answer really doesn't show much about a candidate's ability to code.

Note that you'll get the same behaviour even if A.Foo is virtual and B overrides it.

If you like C# puzzles and oddities, I've got a few too (including this one).