[C++]Related to Copy Constructor

#include <iostream>
using namespace std;

class Simple
{
private:
	int num1;
	int num2;
public:
	Simple(int n1, int n2) : num1(n1), num2(n2)
	{
		// empty
	}
	// Copy Constructor
	// "If undefined Copy constructor, auto insert default COPY CONSTRUCTOR"
	// Parameter of copy constructor MUST BE REFERENCE.
	// Keyword: explicit (for clarity of code)
	// If doesn't want call default copy constructor, should to use this Keyword.
	explicit Simple(const Simple& copy) : num1(copy.num1), num2(copy.num2)
	{
		cout << "Called SoSimple(SoSimple& copy)" << endl;
	}
	
	void ShowInfo() const
	{
		cout << "num1: " << num1 << endl;
		cout << "num2: " << num2 << endl;
		cout << "Addr: " << this << endl;
	}
};

int main(void)
{
	Simple a(1, 2);

	Simple b(a);
	// Generate Object type of 'Simple'
	// Object name is 'b'
	// Object generation is completed through 
	// a call from a constructor who can receive sim1 as a argument.

	// Different Addreess each(Shallow Copy)
	// Equal Member variable value each
	a.ShowInfo();	// 2A342FFBF8
	b.ShowInfo();	// 2A342FFC18



	return 0;
}

/*
The default constructor copies members to members.
This is called shallow copy.
This is a problem if the member variable refers to the memory space of the heap.
*/