#include <complex>
#include <iostream>

using namespace std;

class A {
	public:
		int _num;

		A() : _num(0) {
			cerr << "Constructing new A at " << this << endl;
		}

		A(int num) : _num(num) {
			cerr << "Constructing new A at " << this << endl;
		}

		A(const A &other) : _num(other._num) {
			cerr << "Copying A from " << &other << " to new A at " << this << endl;
		}

		~A() {
			cerr << "Destroying A at " << this << endl;
		}

		A &operator=(const A &other) {
			if (this != &other) {
				cerr << "Changing value of _num in A at " << this << " from value at " << &other << endl;
				this->_num = other._num;
			}

			return *this;
		}
};

A &changeGiven(A &obj, int newnum) {
	cerr << "Changing _num of " << &obj << endl;
	obj._num = newnum;

	return obj;
}

A copyAndChange(A &obj, int newnum) {
	cerr << "Copying and changing _num of " << &obj << endl;
	A newA(obj);
	newA._num = newnum;
	return newA;
}

void changeReference(A &obj, A &obj2) {
	obj = obj2;
}

void changePointer(A *obj, A *obj2) {
	obj = obj2;
}

void changeObject(A obj, A obj2) {
	obj = obj2;
}

int main(int argc, char *argv[]) {
	cerr << "Creating obj1" << endl;
	A obj1(42);
	cerr << endl;

	cerr << "Creating obj2" << endl;
	A obj2(23);
	cerr << endl;

	cerr << "Creating obj3 the hard way" << endl;
	A obj3;
	obj3 = A(5);
	cerr << endl;

	cerr << "Changing obj1" << endl;
	A &obj4 = changeGiven(obj1, 24);
	cerr << "Now obj1._num is " << obj1._num << endl;
	cerr << " ... and obj4._num is " << obj4._num << endl;
	cerr << " ... obj1 is at " << &obj1 << endl;
	cerr << " ... obj4 is at " << &obj4 << endl;
	cerr << endl;

	cerr << "Changing obj2" << endl;
	const A &obj5 = copyAndChange(obj2, 32);
	cerr << "Now obj2._num is " << obj2._num << endl;
	cerr << " ... and obj5._num is " << obj5._num << endl;
	cerr << " ... obj2 is at " << &obj2 << endl;
	cerr << " ... obj5 is at " << &obj5 << endl;
	cerr << endl;

	cerr << "Changing reference obj3 = obj1" << endl;
	changeReference(obj3, obj1);
	cerr << "Now obj3._num is " << obj3._num << endl;
	cerr << " ... and obj1._num is " << obj1._num << endl;
	cerr << " ... obj3 is at " << &obj3 << endl;
	cerr << " ... obj1 is at " << &obj1 << endl;
	cerr << endl;

	cerr << "Changing pointer obj3 = obj2" << endl;
	changePointer(&obj3, &obj2);
	cerr << "Now obj3._num is " << obj3._num << endl;
	cerr << " ... and obj2._num is " << obj2._num << endl;
	cerr << " ... obj3 is at " << &obj3 << endl;
	cerr << " ... obj2 is at " << &obj2 << endl;
	cerr << endl;

	cerr << "Changing object obj3 = obj1" << endl;
	changeObject(obj3, obj1);
	cerr << "Now obj3._num is " << obj3._num << endl;
	cerr << " ... and obj1._num is " << obj2._num << endl;
	cerr << " ... obj3 is at " << &obj3 << endl;
	cerr << " ... obj1 is at " << &obj2 << endl;
	cerr << endl;
}