cppPointersAdvExamples

#include <iostream>

void printArr(int arr[], int arrSize)
{
    for (int i{ 0 }; i < arrSize; ++i)
    {
        std::cout << arr[i] << ' ';
    }
    std::cout << '\n';
}

void printArr(int arr[], int idxBegin, int idxEnd)
{
    for (int i{ idxBegin }; i < idxEnd; ++i)
    {
        std::cout << arr[i] << ' ';
    }
    std::cout << '\n';
}

void printArr(int* begin, int* end)
{
    while (begin != end)
    {
        std::cout << *begin++ << ' ';
    }
    std::cout << '\n';
}

void fillArr(int* begin, int* end)
{
    while (begin != end)
    {
        *begin++ = rand()%10;
    }
    std::cout << '\n';
}

int main()
{
    const int arrSize{ 10 };
    int arr[arrSize]{ 1,2,3,4,5,6,7,8,9,10 };

    int* ptr{ arr + 4 }; // 100

    int* begin{ arr };
    int* end{ arr + arrSize };


    printArr(arr, 3, 8);
    printArr(arr + 3, arr + 8);

    fillArr(arr + 3, arr + arrSize - 3);
    printArr(arr, arr + arrSize);


    int num{ 42 };
    const int answer{ 42 };
    const int badAnswer{ -15 };
    int* ptrI{ &num };
    const int* ptrIC{ &num };
    int* const beginArr{ arr };
    const int* const zhest{ arr };

    int* ptr;                   //simple pointer                pointer - rw    *pointer - rw
    const int* ptrC;            //pointer to constant           pointer - rw    *pointer - ro
    int* const cPtr{};          //constant pointer              pointer - ro    *pointer - rw
    const int* const cPtrC{};   //constant pointer to constant  pointer - ro    *pointer - ro

    int* point{ nullptr };
    point = &num; // single variable
    point = arr; // array begin, multipe variables




    std::cout << *ptrIC << '\n';
    //*ptrI = 100500;
    ptrIC = &num;
    *ptrIC = 100500;
    std::cout << *ptrIC << '\n';

    //int num{42}; //4
    //int num1{ 33 };

    //float val{ 42 }; // 4

    //bool flag{}; // 1

    //uint16_t word{ 1005 }; // 2

    //double temp{ 36.675 };

    //std::cout << "num is living at " << *(&num) << " address\n";
    //std::cout << "val is living at " << *(&val) << " address\n";
    //std::cout << "flag is living at " << *(&flag) << " address\n";

    ////int address{ (int)&num };

    ////std::cout << " address = " << address << '\n';


    ////void fun(int par);
    ////void fun(int* par);

    ////fun(0);
    ////fun(NULL);
    ////fun(nullptr);
    ////nullptr_t
    //// nullptr
    //int* ptrNum{nullptr}; //4
    //bool isNull{ nullptr };

    //std::cout << "In ptrNum is address: "<< ptrNum << '\n';
    //std::cout << std::boolalpha << isNull << '\n';
    //
    //{
    //  int shortLifeVar{ 1111 };
    //  ptrNum = &shortLifeVar;

    //  std::cout << "Inside block *ptrNum = " << *ptrNum << '\n';
    //}

    //std::cout << "Outside block *ptrNum = " << *ptrNum << '\n';

    //if (ptrNum)
    //{
    //  std::cout << *ptrNum << '\n';
    //}
    //else
    //{
    //  std::cout << "nullptr detected! cannot dereference!!\n";
    //}



    //[100][104][108][112][116][120][124][128][132][136]
    // 5
    //100 + 5 * sizeof(int)
    //100 + 5 * 4
    //100 + 20 -> 120


    //ptr = ptr + 2; // 100 + 2 * sizeof(int) -> 100 + 2 * 4 -> 100 + 8 -> 108
    //
    //std::cout << *ptr << '\n';
    //--ptr; // 108 - 1 * sizeof(int)  - > 108 - 4 -> 104
    //std::cout << *ptr << '\n';

    //std::cout << *(arr + 1) << " < = > " << ptr[1] << '\n';

    // *(ptr + i) < = > ptr[i]


    //for (int i{ 0 }; i < arrSize; ++i)
    //{
    //  //std::cout << "Address: " << ptr + i << " = " << *(ptr + i) << '\n';
    //  std::cout << *arr << " < = > " << ptr[0] << '\n';
    //}
    // *(ptr + i) < - > arr[i] < - > ptr[i]

    /*std::cout << std::boolalpha << (&arr[0] == &arr[0]) << '\n';

    std::cout << std::boolalpha << (&arr[0] <= &arr[0]) << '\n';*/
    //std::cout << arr << '\n';





    //while (begin != end)
    //{
    //  std::cout << *begin++ << ' ';
    //}
    //std::cout << '\n';

    //int size;

    //std::cout << "Enter array size:\n";
    //std::cin >> size;
    //int* ptr{ new int[size] {1,2,3,4,5,6,7,8,9,10,11,12} };
    //begin = ptr;
    //end = ptr + size;

    //while (begin != end)
    //{
    //  std::cout << *begin++ << ' ';
    //}
    //std::cout << '\n';


    //delete[] ptr;

    return 0;
}