#include <iostream>
#include <memory> // smart pointer header

#include "functions.h"

using namespace std;

int main()
{
	// general
	int* pNumber = nullptr;
	pNumber = new int(0);

	cout << "pNumber: " << pNumber << endl;
	cout << "*pNumber: " << *pNumber << endl;
	cout << "size of pointer: " << sizeof(pNumber) << endl;
	cout << "size of *pointer: " << sizeof(*pNumber) << endl;

	*pNumber = 567;

	//pNumber = new int(0); // BAD BAD - Memory Leak, because we overriding an existing pointer address with a new one

	// here are 100s line of code OR at different position

	if (pNumber != nullptr)
	{
		delete pNumber;
		pNumber = nullptr;
	}

	// pointer as references
	int number = 10;
	changeInteger(number);
	changeIntegerPerPointer(&number);
	changeIntegerPerPointer(pNumber);
	changeIntegerPerReference(number);
	//changeIntegerPerReference(10); // doesn't work, because you need an existing & initialized variable for a reference

	// smart pointer
	// unique_ptr - only one owner exist for the object
	// shared_ptr - can have multiple owners
	// weak_ptr - is a loose connection to a shared_ptr

	unique_ptr<int> pNumber2 = make_unique<int>(10);
	*pNumber2 = 100;
	//unique_ptr<int> pNumber3 = pNumber2; // compiler error - you can't create a copy of an unique pointer
	unique_ptr<int> pNumber4 = make_unique<int>(*pNumber2);

	shared_ptr<int> pNumber5 = make_shared<int>(10);
	shared_ptr<int> pNumber6 = pNumber5;
	*pNumber6 = 100;

	pNumber5.reset();

	weak_ptr<int> pNumber7 = pNumber6;
	//*pNumber7 = 1000; // compiler error, because a weak pointer has no direct access to the shared pointer, you have to create a shared pointer object

	if (!pNumber7.expired())
	{
		shared_ptr<int> pTmpSharedPointer = pNumber7.lock();
		*pTmpSharedPointer = 10000;
	}

	pNumber6.reset();
	shared_ptr<int> pTmpSharedPointer2 = pNumber7.lock();
	if (pTmpSharedPointer2 != nullptr) *pTmpSharedPointer2 = 10; // smart pointer are no guarantee for a valid object behind the pointer

	return 0;
}