• By default, C++ compiler creates a copy constructor to copy counterparts from one object to another. When class has dynamic memory allocation, define our own copy constructor
• When to call copy constructor
  • When you declare a new object and initialize it with another object
  • When pass an object to function by value
  • When an object is constructed based on another object of the same class
  • When explicity invoked in another constructor's initialization list
  • When an object is a data member of another class for which the compiler has generated its own copy constructor

• Whenever you are writing either one of destructor, copy constructor or copy assignment operator, you probably need to write the other two

#ifndef V_H
#define V_H
class V
{
	private:
		int size;
		int *array;
	public:
		//constructor
		V(int s):size(s)
		{
			array = new int[size];
			for(int i = 0; i < size; i++)
				array[i] = 10*i;
		}
 
		//copy constructor
		V(const V &right):size(right.size), array(size?new int[size]:nullptr)
		{
			std::cout<<"Copy Constructor ..."<<std::endl;
			std::copy(right.array, right.array+size, array);
			std::cout<<"End Constructor ..."<<std::endl;
		}
 
		int *getAddress() const {return array;}
 
		void display() const
		{
			for(int i = 0; i < size; i++)
				std::cout<<array[i]<<" ";
			std::cout<<std::endl;
		}
 
		//copy assignment
		const V& operator=(const V &right)
		{
			std::cout<<"Copy Assignment ..."<<std::endl;
			V temp(right);
			std::swap(size, temp.size);
			std::swap(array, temp.array);
			return *this;
		}
 
		~V()
		{
			std::cout<<"Destructor ..."<<std::endl;
			delete [] array;
			array = 0;
			size = 0;
		}
};
#endif
			

#include <iostream>
#include "V.h"
 
int main(int argc, char *argv[])
{
	V v1(10);
	V v2(v1);
	V v3 = v1;
 
	v2.display();
	v3.display();
 
	return 0;
}
			

#include <iostream>
#include "V.h"
 
void getObject(V v)
{
	v.display();
}
 
int main(int argc, char *argv[])
{
	V v(10);
 
	std::cout<<"Before calling function ..."<<std::endl;
	getObject(v);
	std::cout<<"After calling function ..."<<std::endl;
 
	return 0;
}
			

#ifndef V_H
#define V_H
class V
{
	private:
		int size;
		int *array;
	public:
		//constructor
		V(int s):size(s)
		{
			array = new int[size];
			for(int i = 0; i < size; i++)
				array[i] = 10*i;
		}
 
		V(int s, V right):size(s), array(size?new int [size]:nullptr)
		{
			std::cout<<"Second Constructor ..."<<std::endl;
			std::copy(right.array, right.array+size, array);
		}
 
		//copy constructor
		V(const V &right):size(right.size), array(size?new int[size]:nullptr)
		{
			std::cout<<"Copy Constructor ..."<<std::endl;
			std::copy(right.array, right.array+size, array);
			std::cout<<"End Constructor ..."<<std::endl;
		}
 
		int *getAddress() const {return array;}
 
		void display() const
		{
			for(int i = 0; i < size; i++)
				std::cout<<array[i]<<" ";
			std::cout<<std::endl;
		}
 
		//copy assignment
		const V& operator=(const V &right)
		{
			std::cout<<"Copy Assignment ..."<<std::endl;
			V temp(right);
			std::swap(size, temp.size);
			std::swap(array, temp.array);
			return *this;
		}
 
		~V()
		{
			std::cout<<"Destructor ..."<<std::endl;
			delete [] array;
			array = 0;
			size = 0;
		}
};
#endif
			

#include <iostream>
#include "V.h"
 
int main(int argc, char *argv[])
{
	V v(10);
	V v2(20, v);
 
	v2.display();
 
	return 0;
}
			

• Name(string f, string l):firstName(f), lastName(l){}

#ifndef V_H
#define V_H
class V
{
	private:
		int size;
		int *array;
	public:
		//constructor
		V()
		{
			std::cout<<"Default Constructor ..."<<std::endl;
			size = 0;
			array = 0;
		}
 
		V(int s):size(s)
		{
			array = new int[size];
			for(int i = 0; i < size; i++)
				array[i] = 10*i;
		}
 
		//copy constructor
		V(const V &right):size(right.size), array(size?new int[size]:nullptr)
		{
			std::cout<<"Copy Constructor ..."<<std::endl;
			std::copy(right.array, right.array+size, array);
			std::cout<<"End Constructor ..."<<std::endl;
		}
 
		int *getAddress() const {return array;}
 
		void display() const
		{
			for(int i = 0; i < size; i++)
				std::cout<<array[i]<<" ";
			std::cout<<std::endl;
		}
 
		//copy assignment
		const V& operator=(const V &right)
		{
			std::cout<<"Copy Assignment ..."<<std::endl;
			V temp(right);
			std::swap(size, temp.size);
			std::swap(array, temp.array);
			return *this;
		}
 
		~V()
		{
			std::cout<<"Destructor ..."<<std::endl;
			delete [] array;
			array = 0;
			size = 0;
		}
};
#endif
			

#ifndef A_H
#define A_H
#include <iostream>
#include <string>
#include "V.h"
 
class A
{
	private:
		std::string name;
		V array;
	public:
		A(std::string n, V v)
		{
			std::cout<<"--------------"<<std::endl;
			name = n;
			array = v;
			std::cout<<"--------------"<<std::endl;
		}
};
#endif
			

#include <iostream>
#include "A.h"
#include "V.h"
 
int main(int argc, char *argv[])
{
	V v(10);
	A a("Array", v);
 
	return 0;
}