#include <iostream>
#include <cstdlib>
using namespace std;

class duo {
	int member1;
	int member2;
public:
	duo(int initial_member1, int initial_member2);
};

class mono {
	int member1;
public:
	mono(int initial_member1);
	mono(const mono& another);   //copy constructor
};

class zero {
public:
	zero();
};

int main()
{
	duo d1(10, 20);
	//duo d2;         //won't compile: constructor needs arguments

	mono m1(10);
	mono m2 = 10;     //another way to do the same thing when the
	                  //constructor has exactly one argument

	//zero z1();      //creates no object, calls no constructor
	zero z2;          //call a constructor that has no arguments

	int i = 10;
	int j(10);        //another way to do same thing

	mono m3 = m1;      //call copy constructor: m3.mono(m1)

	return EXIT_SUCCESS;
}

duo::duo(int initial_member1, int initial_member2)
{
	cout << "constructor for duo\n";
	member1 = initial_member1;
	member2 = initial_member2;
}

mono::mono(int initial_member1)
{
	cout << "constructor for mono\n";
	member1 = initial_member1;
}

mono::mono(const mono& another)   //copy constructor
{
	cout << "copy constructor for mono\n";
	member1 = another.member1;
}

zero::zero()
{
	cout << "constructor for zero\n";
}