#include <iostream>
#include <memory>
#include <ostream>

void changeInt(int n);

void changeIntPointer(int *pN);

void changeIntReference(int &n);

void createInt(int *pN);

void createInt(int **ppN);

int main() {
    int i = 5;
    int *pI = nullptr;
    pI = &i;
    *pI = 10;
    pI = new int;
    pI = new int(); // CAUTION - memory leak created
    pI = new int(10); // CAUTION - memory leak created
    delete pI;
    pI = nullptr;

    int &rI = i; // reference

    changeInt(i);
    changeIntPointer(&i);
    changeIntReference(i);

    createInt(pI);
    createInt(&pI);

    // const
    // const int ci = 5; // constant integer
    // const int* cpi = new int(0); // pointer to a constant integer
    // cpi = new int(10);
    // *cpi = 10;
    // int const * pci = new int(0); // pointer to a constant integer
    // pci = new int(10);
    // *pci = 10;
    // int * const pic = new int(0); // constant pointer to an integer
    // pic = new int(10);
    // *pic = 10;
    // const int * const cpic = new int(0); // constant pointer to a constant integer
    // cpic = new int(10);
    // *cpic = 10;
    // int const * const pcic = new int(0); // constant pointer to a constant integer
    // pcic = new int(10);
    // *pcic = 10;
    // const int const * cpci = new int(0);
    // const int const * const cpcic = new int(0);

    std::unique_ptr<int> upi = std::make_unique<int>(10);
    // std::unique_ptr<int> upi2 = upi; // don't work
    std::unique_ptr<int> upi3 = std::make_unique<int>(*upi);

    std::shared_ptr<int> spi = std::make_shared<int>(10);
    std::shared_ptr<int> spi2 = spi;
    spi.reset();

    std::weak_ptr<int> wpi = spi2;
    if (wpi.expired()) {
        std::cout << "expired" << std::endl;
    } else {
        std::cout << "not expired" << std::endl;
        std::shared_ptr<int> spi3 = wpi.lock();
    }

    spi2.reset();

    if (wpi.expired()) {
        std::cout << "expired" << std::endl;
    } else {
        std::cout << "not expired" << std::endl;
    }

    return 0;
}

void changeInt(int n) {
    n *= 2;
}

void changeIntPointer(int *pN) {
    if (pN == nullptr) return;
    *pN *= 2;
}

void changeIntReference(int &n) {
    n *= 2;
}

void createInt(int *pN) {
    pN = new int(10);
}

void createInt(int **ppN) {
    if (ppN == nullptr) return;
    *ppN = new int(10);
}