Question 11 :
What is the difference between an interface and abstract class?
In the interface all methods must be abstract; in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.
Question 12 :
What is an abstract class?
A class that cannot be instantiated. A concept in C++ known as pure virtual method. A class that must be inherited and have the methods over-ridden. Essentially, it is a blueprint for a class without any implementation.
Question 13 :
Does C# support multiple-inheritance?
Question 14 :
Who is a protected class-level variable available to?
It is available to any sub-class (a class inheriting this class).
Question 15 :
Can you store multiple data types in System.Array?