Virtual base class in C++ OOP

What is a Virtual base class?

The virtual base class is very helpful in virtual inheritance.

When we use multiple inheritances, then multiple “instances” of a given class appearing in an inheritance hierarchy. It leads to redundancy. Redundancy is not good in such a scenario.

When we declare a class as a virtual class, then it means that we are helping the compiler that we only required a single instance.

Why we use a virtual base class?

Virtual base class means that child classes can access the base classes virtually from a long distance in the parent-child hierarchy.

How to declare a class as a virtual base class?

class A {
public:
int number;
A()
{
int number = 10;
}
};
class B : public virtual A {};
class C : public virtual A {};
class D : public B, public C{};

Explanation of Diagrams

Class A:Base Parent Class

Class B:  B is child class of class A.

Class C: C is a child class of class A.

Class D: D is a child class of class B and Class C. A is the grandfather of class D.

Step 1:

  1. Create class A
  2. declare the variable “int number” inside class A.
  3. Class C and Class B get the “int number” variable from class A.
  4. Class D is getting the “int number” from both class B, and Class C. This is not good to do.

Virtual-base-class-in-C

We must avoid this redundancy and never inherit the same member(e.g int number) from multiple parent classes.

Virtual base class inheritance in child classes in C++

The solution to solve the above-mentioned problem is to make the parent base class a virtual class.

How to inherit from Virtual base class

Here, Class D is getting the “int number” directly from the parent base virtual class.

C++ Program  of Virtual base class

Let us code the above-mentioned scenario with C++.

Output

number=3

virtual class in C++ OOP

Example 2 with error

Example 2 without error

Video Lecture

Virtual Base Class Exercise Solution

  1. Write a C++ Program to display the reverse of a number using the Virtual base Class in Object Oriented Programming(OOP).
  2. Write a program in C++ to convert a decimal number into binary without using an array and using the Virtual base Class in Object Oriented Programming(OOP).
  3. Write a C++ program to find HCF (Highest Common Factor) of two numbers using the Virtual base Class in Object Oriented Programming(OOP).
  4. C++ program to print rhombus or parallelogram star pattern using the Virtual base Class in Object Oriented Programming(OOP).
  5. Write a C program to check whether a number is a Strong Number or not using the Virtual base Class in Object Oriented Programming(OOP).
  6. Write a program in C++ to find the prime numbers within a range of numbers by using the Virtual base Class in Object Oriented Programming(OOP).
  7. Write a program in C++ to convert a decimal number into octal without using an array and Virtual base Class in Object Oriented Programming(OOP).
  8. Write a C++ program to display Pascal’s triangle using Virtual base Class in Object Oriented Programming(OOP).
  9. C++ program to print hollow rhombus, parallelogram star pattern using the Virtual Base Class.
  10. C++ program to print mirrored right triangle star pattern using virtual base class.
  11. Write a program in C++ to display the sum of the series by using the virtual base class.
  12. Write a C++ program to find Strong Numbers within a range of numbers by using the virtual base class.
  13. Write a program in C++ to display the cube of the number up to a given integer by using the virtual base class. 
  14. Write a program in C++ to check Armstrong number of n digits by using the virtual base class. 
  15. Write a program in C++ to print a string in reverse order by using the virtual base class. 
  16. Write a C++ program to find the perfect numbers within a given number of range by using the virtual base class. 
  17. Write a C++ Program to display the pattern like a pyramid using the alphabet by using the virtual base class. Solution
  18. Write a program in C++ to display the n terms of odd natural number and their sum. Solution
  19. Write a program in C++ to make such a pattern like a pyramid with a number that will repeat the number in the same row. 
  20. Write a program in C++  to Check Whether a Number can be Express as Sum of Two Prime Numbers by using the virtual base class. 
  21. Develop a C++ program to print a hollow square or rectangle star pattern by using the virtual base class. 
  22. Write a program in C++ to convert an Octal number to a Decimal number by using the virtual base class. 
  23. Write a program in C++ to find the number and sum of all integer between 100 and 200 which are divisible by 9. 
  24. Write a program in C++ to make such a pattern like a pyramid with numbers increased by 1 by using the virtual base class.
  25. C++ program to print the hollow right triangle star pattern by using the virtual base class in object-oriented programming. 
  26. Write a C++ program to find out the sum of an A.P. series by using the virtual base class. 
  27. Write a program in C++ to display the pattern like a diamond by using the virtual base class. 
  28. Fibonacci Series Program in C++ with virtual inheritance.
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