Accessing derived class variable through object of base class in C#

Question

I have code as follows Declare.cs

Class B { }
Class D1 : B { public var1 }
Class D2 : B {}
B Baseobject = new B();
if(baseobject is D1){ Console.print(B.var1) }

When I compile this scenario I always get compiler error that var1 is not accessible to B . If var1 always needs to be in D1 is there way to resolve this?

Answer 1

The object needs to be an instance of D1, so your example is a bit wrong.

You then need to cast your object to D1.

B baseObject = new D1();
Console.WriteLine(((D1)baseObject).var1);

Answer 2

First of all, it won't compile because you need to cast. Why do you need to cast? Because your object reference is a type of B and knows nothing about D1 type and its methods and properties. You need to read a bit more about basic OOP principles