Answer to Question #213954 in C++ for Muhammad danyal

Question

a)   Can we declare base class constructor or destructor as virtual if yes then why we want to do?

b)   How we can declare a class as abstract and why we need abstract classes?          

c)    Why we cannot able to create objects of abstract classes give reasonable justification of that.                   

Answer 1

a) A base class constructor cannot be declared as virtual.

A base class destructor can be declared as virtual. Virtual makes sure the destructor starts at the top instead of the middle

b)

Abstract class helps in information hiding

class Shape {
    public:

      // creating a pure virtual function
      virtual void calculateArea() = 0;
}

c) A object of abstract class  cannot be created because there is an abstract method which has nothing.