access supper class method with the instance hirarical base

Question

Dear All I faced one interview question in polaris They asked me to print the virtual method of the super class with the instance of B class. Is it possible by casting? if so please try and let me know. class hirarical { public virtual void print() { Console.WriteLine(print virtual method); } public void printnorm() { Console.WriteLine(print virtual method); } } class a : hirarical { public override void print() { Console.WriteLine(print a method); //base.print(); } } class B : a { public override void print() { //need to access the virtual method of hierarical class with B instance can do casting with B instance Console.WriteLine(print B method); } } //need to access the

Vulpes · Answer

Well as I said at the start of my previous post you can always do this from the B class: var h = new hirarical(); h.print(); but unless it was something you really had to do this would be bad programming IMO. I can't think of any other way to do this using a cast or otherwise. In fact I just did a quick google and came up with this thread where the Microsoft poster Paul Zhou appears to be agreeing with us on this: https://social.msdn.microsoft.com/Forums/vstudio/en-US/6a66b00d-e150-4852-abbd-2a37e7a9e4eb/how-to-call-a-virtual-method-of-an-ancestor-class-that-is-higher-than-the-base-class?forum=clr

Yadlapalli Srikanth · Answer

Hi vipul Thank you for the reply I told the same to the interviewer he was not agreed with me. Can you please check any alternate solution is there.

Vulpes · Answer

Unless you actually create an object of the hirarical class from B then you can't call its virtual print() method directly from B. This is because B's base class 'a' has already overridden the print() method and so invoking base.print() from B will always call a's implementation. Casting is of no use in these scenarios either and this line would actually cause a stack overflow exception: ((hirarical)this).print(); because B's print() method would be called repeatedly. However if you can change 'a' as well as B you can do this: using System; class hirarical { public virtual void print() { Console.WriteLine(print virtual method); } public void printnorm() { Console.WriteLine(print virtual method); } } class a : hirarical { public override void print() { base.print(); // calls hirarical.print() Console.WriteLine(print a method); } } class B : a { public override void print() { //need to access the virtual method of hirarical class with B instance base.print(); // calls a.print() Console.WriteLine(print B method); } } class Program { static void Main() { B b = new B(); b.print(); Console.Readkey(); } } The output is: print virtual method print a method print B method I'm not sure why there's also a non-virtual printnorm() method in the hirarical class which also writes 'print virtual method' to the console unless this is a trick question and you're suppose to call that instead. To do so then of course a cast works as it's non-virtual: ((hirarical)this).printnorm();