Constructor Example in C++

The program defines a class named Rectangle with two data members length and breadth. It also defines four member functions, including two constructors and two member functions to calculate the area and perimeter of the rectangle.

The first constructor is a default constructor that initializes the length and breadth of the rectangle to 0. The second constructor is a parameterized constructor that takes two integer arguments and initializes the length and breadth of the rectangle with those arguments.

The program also defines a copy constructor that creates a new Rectangle object and initializes it with the data members of another Rectangle object passed to it as an argument. The main function creates three Rectangle objects: o1, o2, and o3. o1 is created using the default constructor, o2 is created using the parameterized constructor with arguments 10 and 5, and o3 is created using the copy constructor with argument o2.

The main function then prints the area of each Rectangle object using the area() member function of the Rectangle class. The area of o1 is 0, the area of o2 is 50, and the area of o3 is 50.

Source Code

#include<iostream>
using namespace std;
class Rectangle
{
private:
    int length;
    int breadth;
public :
    Rectangle() //Default Constructor
    {
        length=0;
        breadth=0;
    }
    Rectangle(int l,int b) //Parameterized Constructor
    {
        length=l;
        breadth=b ;
    }
    /*
      Rectangle(int l=0,int b=0) //Parameterized Constructor Default Arguments
        {
            length=l;
            breadth=b ;
        }
    */
    Rectangle(Rectangle &o2)
    {
        length=o2.length;
        breadth=o2.breadth;
    }
    //Constructor Overloading
    int area()
    {
        return length*breadth;
    }
    int perimeter()
    {
        return 2*(length+breadth);
    }
};
int main()
{
    Rectangle o1,o2(10,5),o3(o2);
    cout<<"\nArea : "<<o1.area();
    cout<<"\nArea : "<<o2.area();
    cout<<"\nArea : "<<o3.area();
    return 0;
}

To download raw file Click Here

Output

Area : 0
Area : 50Area : 50

Program List

Flow Control

IF Statement Examples

Switch Case

Goto Statement

Break and Continue

While Loop

Do While Loop

For Loop

Friend Function in C++

String Examples

Array Examples

Structure Examples

Structure & Pointer Examples

Structure & Functions Examples

Enumeration Examples

Template Examples

Functions

Inheritance Examples

Hierarchical Inheritance

Hybrid Inheritance

Multiplication using Hybrid Inheritance

Multilevel Inheritance

Multiple Inheritance

Single Level Inheritance

Class and Objects

Constructor Example

Destructor Example

Destructor Example in C++

Operator Overloading Example

Operator and Function Example

Display Values using Friend Function