Object Oriented Programming Concepts & Questions

1. What is Dynamic Binding? 

• Binding means the link between procedure call and code to be executed.
• Dynamic binding means link exists between procedure call and code to be executed at   run time when that procedure is called.
• It is also known late binding. 
• It is generally used with polymorphism and inheritance.
• For example, compiler comes to know at runtime that which function of 'sum' will be called either with two arguments or with three arguments.

  2. What is the difference between Dynamic Binding in C++ and Java? 

There’s no virtual keyword in Java because all non-static methods always use dynamic binding. In Java, the programmer doesn’t have to decide whether or not to use dynamic binding. 

Virtual Function is a function in the base class, which is overridden in the derived class, and which tells the compiler to perform dynamic Binding on this function. The reason virtual exists in C++ is so you can leave it off for a slight increase in efficiency when you’re tuning for, but this often results in confusion and unpleasant surprises. 

The final keyword in Java provides some efficiency tuning – it tells the compiler that this method may not be overridden, and thus that it can be statically bound. In C++, we can do that by using a non-virtual call. 

3. What is one programming situation where multiple inheritance has significant advantage over interfaces?

Interface just carry "method signatures", whereas classes carry actual behavior. Multiple inheritance greatly helps to reduce code.

4. What are the design issues of OOP languages? 

- What non-objects are in the language?

- Are Subclasses Subtypes? If so, derived objects can be legally used wherever a parent object could be used.

- Type Checking and Polymorphism

- Single and Multiple Inheritance. Inherit from 1 (or more than 1) parent.

- Object Allocation and Deallocation. Are objects allocated from heap or stack?

- Dynamic and Static Binding. When are messages bound to methods, before or during run-time?

- Nested Classes. Can a class be nested inside another class?

- Initialization of Objects. Are objects initialized when created? Implicit or explicit?