Accessing a property of derived class from the base class in C#

Question

In C#, what is the best way to access a property of the derived class when the generic list contains just the base class.

public class ClassA : BaseClass
{
          


        

Answer 1

You might have some issues with Generics and subclasses (in which case you should go back to System.Collections.ArrayList), but you have to cast the BaseClass to the subclass you wish to use. If you use the 'as' directory, it will succeed if the BaseClass can be casted to the subclass, or it will be null if it cannot be cast. It would look something like:

for(int i = 0; i < MyList.Count; i++)
{
    BaseClass bc = MyList[i];
    ClassA a = bc as ClassA;
    ClassB b = bc as ClassB;
    bc.BaseClassMethod();
    if (a != null) {
       a.PropertyA;
    }
    if (b != null) {
       b.PropertyB;
    }
}

Also, I should mention that this smells a bit bad. This is the kind of code that indicates a poorly structured object heirarchy. In general, if you can't say a IS A BaseClass, your design is probably wrong. But, hope that helps!