lesson_321_22

#include <iostream>

using namespace std;

void test_myswap();
void test_myswap_by_pc();
void myswap(int& x, int& y);
void test_checsign();
bool checsign(int, int*, int&, int&);

int sum(int a, int b) {
    return a + b;
}

void pointer_vs_constant() {
    /*
    c - const
    p - pointer
    r - reference
    */

    int x = 17;
    int y = 22;
    x = x + 12;
    cout << x << endl;

    const int cx = x;
    cout << cx << endl;
    x = x + 1000;
    cout << cx << endl;
    cout << x << endl;
    cout << "sum(x, cx) : " << sum(x, cx) << endl;

    const int* pcx = &cx;
    cout << "*pcx: " << *pcx << endl;

    const int cArr[]{5,6,7,8};
    const int* pca = cArr;
    //cArr[0] = 6;
    //*pca = 6;
    cout << "Const1 " << *pca << endl;
    pca = pca + 1;
    cout << "Const2 " << *pca << endl;
    pca = &x; // это замороченный момент

    const int* const cpcx = &(cArr[2]);
    //cpcx = cpcx + 1;
    //*cpcx = 888;

    int z = 33;
    int* const cpz = &z;
    cout << z << " " << *cpz << endl;
    //cpz++;
    *cpz = 44;
    cout << z << " " << *cpz << endl;
    z = 55;
    cout << z << " " << *cpz << endl;

    //*pcx = 14;     - даже через разъименование нельзя
    //myswap(x, cx); - ссылка привела бы к изменению - так нельзя
    //cx++;          - константы нельзя менять

}

int main() {
    //test_checsign();
    //test_myswap();
    //test_myswap_by_pc();
    pointer_vs_constant();
    return 0;
}


/// <summary>
/// Count numbers of positive and negative elements in array
/// </summary>
/// <param name="size">A integer size of array</param>
/// <param name="arr">A array of int</param>
/// <param name="n_neg">Nuber of negative</param>
/// <param name="n_pos">Number of positive</param>
/// <returns>Is error in the function</returns>
bool checsign(int size,   // size
    int* arr,   //
    int& n_neg, //
    int& n_pos  //
) {
    n_neg = 0;
    n_pos = 0;
    for (int k = 0; k < size; k++) {
        if (arr[k] < 0) n_neg++;
        else if (arr[k] > 0) n_pos++;
    }
    return false;
}

void test_checsign() {
    int arr[]{ 1, 3, 0, -2, 1,-1, 12, 7 };
    int n_neg = 0;
    int n_pos = 0;
    bool is_err = checsign(size(arr), arr, n_neg, n_pos);
    if (is_err) {
        cout << "BAD error" << endl;
    }
    if (n_pos != 5) {
        cout << "BAD value positive wrong" << endl;
    }
    if (n_neg != 2) {
        cout << "BAD value negative wrong" << endl;
    }
    if (!is_err && (n_pos == 5) && (n_neg == 2)) {
        cout << "OK";
    }
}

void myswap4(int x, int y) {
    // BAD
    int temp = x;
    x = y;
    y = temp;
    cout << "In: " << x << " " << y << endl;
}

void myswap3(int* px, int* py) {
    // BAD
    int* temp = px;
    px = py;
    py = temp;
    cout << "In: " << *px << " " << *py << endl;
}

void myswap2(int* px, int* py) {
    // SO SO
    int temp = *px;
    *px = *py;
    *py = temp;
    cout << "In: " << *px << " " << *py << endl;
}

void myswap(int& x, int& y) {
    int temp = x;
    x = y;
    y = temp;
    cout << "In: " << x << " " << y << endl;
}

void myswap_alg(int& x, int& y) {
    x = x + y;
    y = x - y;
    x = x - y;
}

void test_myswap() {
    int x = 4;
    int y = 5;
    swap(x, y);

    cout << x << " " << y << endl;
    // out: 4 5
    myswap(x, y);
    cout << "Out: " << x << " " << y << endl;
    // out: 5 4
}

void test_myswap_by_pc() {
    int x = 4;
    int y = 5;
    cout << "Part 1: ";
    if (x == 4 && y == 5)
        cout << "OK" << endl;
    else
        cout << "BAD" << endl;
    myswap(x, y);
    cout << "Part 2: ";
    if (x == 5 && y == 4)
        cout << "OK" << endl;
    else
        cout << "BAD" << endl;
}