#include <iostream>

using namespace std;

void changeInteger(int n);
void changeIntegerPerPointer(int* pN);
int changeIntegerPerReturn(int n);
void changeIntegerPerReference(int& n);

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

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

	*pNumber = 567;

	//pNumber = new int(0); // BAD BAD - Memory Leak, because we override an existing pointer address with a new one without saving the old one
	
	// here are 100s of lines of code
	
	if (pNumber != nullptr)
	{
		delete pNumber;
		pNumber = nullptr;
	}

	// pointer as references
	int number = 0;
	changeInteger(number);
	changeIntegerPerPointer(&number);
	changeIntegerPerPointer(pNumber);
	changeIntegerPerReference(number);

	return 0;
}

void changeInteger(int n)
{
	n = 100;
}

void changeIntegerPerPointer(int* pN)
{
	cout << "address of pN: " << &pN << endl;

	if (pN == nullptr) return; // BE CAREFUL - if you don't what you get, do a test before

	*pN = 200;
}

void changeIntegerPerReference(int& n)
{
	n = 300;
}