Copy Constructor in C++

    The copy constructor is a constructor that initializes a object with the data values of      another  object is called copy constructor.

    The copy constructor is used to:

• ·        Copy constructor takes one parameter of its  class &object.
• ·        Copy an object to pass it as an argument to a function.
• ·        Copy an object to return it from a function. 

Syntax/ The most common form of copy constructor is shown here −

Class-name (class-name &obj)

{

        // body of copy constructor

}

 

A program that copy constructors is given as follows.

#include<iostream>

using namespace std;

class C {

        private:

      int i;

    public:

       C()      

       {

           i=10;

           cout<<"  Default Constructor!! " <<endl;

        }

       C(C &s)     //Copy constructor

       {

           i=s.i;

          cout<<"The Value of  i = " <<i;

       }

 };

int main(){

        C x;               //constructor call

        C a(x);         // copy constructor call

    // C b=x;         // copy constructor call

}

 

 

Output

Default Constructor!!

The Value of i =10

 

Example No.2  Copy Constructor

#include<iostream>

using namespace std;

class disk {

           private:

      int feet;

      float inch;

    public: 

      disk(){ }

       disk(int f, float in)       

       {

           feet=f; 

           inch=in;

        } 

       disk(disk &s)     //Copy constructor

       {

           feet =s.feet;

          inch = s.inch;

             cout<<"Copy Constructor called!! " <<endl;

       }

        void show(){

          cout<<"The Feet = " <<feet<<endlt;

          cout<<"The inch = " <<inch;

        }

 };

int main(){

        disk d1(5,7) ;               //paramerized constructor call

        disk d2=d1;       // copy constructor call

        d2.show();        

}

 

 

Output

Copy Constructor called!!

The Feet= 5

The inche= 7