Program That Demonstrates Use Of Virtual Function In Calculating Area Of Rectangle And Triangle In C++

LEVEL: Beginner

Whats in this post?

  1. Code
  2. Output
  3. Background and Explanation of the code


To copy code: Click View Source “View Source” on the right of this code snippet.

Background and Explanation of the code

In main ( ), we declare pointer ptr of shape class and create an object r1 of derive class rectangle.The user inputs the length and breadth of r1 object.The address of r1 object is assigned to the base class pointer (ptr).The statement

ptr -> cal_area ( );

on execution invokes the cal_area ( ) function of the derive class rectangle as ptr contains the address of r1 object.

Similarly the same function call which occurs in the later part of the program results in execution of cal_area ( ) function corresponding to derive class triangle as ptr now contains the address of triangle’s object (t1).


Enter length and breadth of rectangle  :  20   30

Area of rectangle =  600

Enter base and perpendicular  of triangle  :  10   30

Area of triangle  =   150