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C++ program to demonstrate example of Copy Constructor

Learn about the Copy Constructor in C++, how to implement Copy Constructor in C++ program?
[Last updated : March 02, 2023]

In this program we will learn to create Copy Constructor program in c++ programming language.

Copy Constructor Program in C++

// C++ program to demonstrate example of
// Copy Constructor.

#include <iostream>
using namespace std;

//Class declaration.
class Demo {
    //Private block  to declare data member( X,Y ) of
    //integer type.
private:
    int X;
    int Y;

    //Public block of member function to
    //access data members.
public:
    //Declaration of parameterized constructor to
    //initialize data members.
    Demo(int a, int b);
    //Declaration of copy constructor to
    //initialize data members.
    Demo(const Demo& d);
    //To display output on screen.
    void Display();

}; //End of class

//Definition of parameterized constructor.
Demo::Demo(int a, int b)
{
    X = a;
    Y = b;
}

//Definition of copy constructor.
Demo::Demo(const Demo& d)
{
    X = d.X;
    Y = d.Y;
}

//Definition of Display () member function.
void Demo::Display()
{
    cout << endl
         << "X: " << X;
    cout << endl
         << "Y: " << Y << endl;
}

int main()
{
    //Ctor automatically call when object is created.
    Demo d1(10, 20);

    //Display value of data member.
    cout << endl
         << "D1 Object: " << endl;
    cout << "Value after initialization : ";
    d1.Display();

    //Intialize object with other object using copy constructor
    Demo d2 = Demo(d1); //also write like this :Demo d2(d1);

    //Display value of data member.
    cout << endl
         << "D2 Object: " << endl;
    cout << "Value after initialization : ";
    d2.Display();

    return 0;
}

Output

D1 Object: 
Value after initialization: 
X: 10
Y: 20

D2 Object: 
Value after initialization: 
X: 10
Y: 20