Question

I have an interface IEntity

public interface IEntity{
    bool Validate();
}

And I have a class Employee which implements this interface

public class Employee : IEntity{
    public bool Validate(){ return true; }
}

Now if I have the following code

Employee emp1 = new Employee();
IEntity ent1 = (IEntity)emp1; // Is this a boxing conversion?

If it is not a boxing conversion then how does the cast work?

Answer 1

No, since Employee is a class, which is a reference type rather than a value type.

From MSDN:

Boxing is the process of converting a
value type to the type object or to
any interface type implemented by this
value type. When the CLR boxes a value
type, it wraps the value inside a
System.Object and stores it on the
managed heap. Unboxing extracts the
value type from the object.

The aforementioned MSDN link has further examples that should help clarify the topic.