🟣 OOP · Lesson 48

Virtual Functions

What is Virtual Functions?

Virtual Functions
A virtual function enables run-time polymorphism. When a base class pointer points to a derived object, the derived version is called.

Level
🟣 Object-Oriented Programming

Example File
virtual-functions.cpp

Main Focus
Concept + syntax + practical C++ program

Why should you learn this?

It helps you write correct and readable C++ programs.
It is used repeatedly in school practicals, projects and competitive programming.
It builds the base for advanced topics such as OOP, STL and data structures.

Important Terms

Term	Meaning / Use
virtual	Virtual Functions programming में Virtual use होता है।
overriding	Virtual Functions programming में Overriding use होता है।
base pointer	Virtual Functions programming में Base pointer use होता है।
dynamic binding	Virtual Functions programming में Dynamic binding use होता है।

Syntax / Pattern

C++

virtual void functionName();

Example Program

main.cpp

#include <iostream>
using namespace std;
class Shape{ public: virtual void draw(){ cout << "Shape"; } };
class Circle: public Shape{ public: void draw(){ cout << "Circle"; } };
int main(){ Shape *s = new Circle(); s->draw(); delete s; }

Expected Output

Circle

Program Explanation

draw() is virtual in base class.
Base pointer calls derived Circle version.

Exam Tip: In C++ practical answers, write the logic first, then the program, then expected output. For theory, always include one suitable example.

Where will you use it?

graphics
plugin systems
flexible OOP design

Common Mistakes

Forgetting virtual when using base pointer.
Not making base destructor virtual in polymorphic classes.

Practice Tasks

Create Animal sound example.
Explain dynamic binding.

Summary

Virtual Functions एक ज़रूरी C++ topic है। परिभाषा सीखें, syntax समझें, example program चलाएं और फिर practice tasks हल करके concept मज़बूत करें।