Copy Constructor - programming

Hello everyone and welcome back to NewAgeInformers!!! In previous post we had learned that what is constructors and it's types. Again in this post we will learn another part of it. So lets get started!!!!

 Constructor:-

        When we create a new variable from an object it is called as copy constructor. There are two types of constructors.

 

1) Implicit constructor. 2) Explicit constructor.

In previous post we learned that compiler creates a copy constructor for every class when no copy constructor is defined. This type of constructor is known as  implicit constructor. It is a special type of constructor that a new object is created as a copy of existing object.

Syntax of copy constructor:

Class name(Class name &object)

{

/* Constructors body*/

}

While applying the copy constructor we need to use following syntax:

Classname new_object_name(old_object_name);

let's take an example for better understanding.

#include<iostream.h>

classNAI

{

int a;

public:

NAI();                                        /* default constructor*/

NAI(int b))                                /*parameterized constructor */

{

a=b;

}

NAI(NAI &obj)                          /*copy constructor*/

{

a=obj.a;

}

void show()

{

cout<<a;

}

};

void main()

{

int b;

cout<<”enter numbers”<<endl;

cin>>b;

NAI old(b); /* for calling copy constructor */

paNAI new(old);

cout<<”the original value:”;

old.show();

cout<<”\n new value is: ”;

new.show();

cout<<endl;

getch();

}

In this program there are two main constructors. First is default, second is parameter constructor which we learned in previous post. Note that copy constructor, is always declared as a passing reference parameter. We can not pass the parameter by value.

So this is it. We will look at destructors in upcoming post. Till that bye bye!!!!!
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