30_09_pointers_struct

#include <iostream>
using namespace std;

double hipotenuse(double a, double b) {
    return sqrt(a * a + b * b);
}

void test_pointers() {
    int val = 12;
    cout << val << " " << &val << endl;
    int* pval = &val;
    cout << pval << " " << *pval << endl;

    const int val2 = 13;
    //val2++; // константы менять нельзя
    cout << val2 << " " << &val2 << endl;
    //int* const pval2 = &val2;
    //cout << "before: " << pval2 << " " << *pval2 << endl;
    //pval2 = &val;
    val += 100; // через эту переменную можно менять
    //*pval2 += 100; // через эту нельзя - она const
    //cout << "arfter: " << pval2 << " " << *pval2 << endl;
}

void my_swap0(int a, int b) {
    cout << "in my swap0 before" << endl;
    cout << "a = " << a << " " << "b =" << b << endl;
    cout << "a = " << &a << " " << "b =" << &b << endl;
    int tmp = a;
    a = b;
    b = tmp;
    cout << "in my swap0 after" << endl;
    cout << "a = " << a << " " << "b =" << b << endl;
    cout << "a = " << &a << " " << "b =" << &b << endl;
}


void my_swap1(int *a, int *b) {
    cout << "in my swap0 before" << endl;
    cout << "a = " << *a << " " << "b =" << *b << endl;
    cout << "a = " << a << " " << "b =" << b << endl;
    int tmp = *a;
    *a = *b;
    *b = tmp;
    cout << "in my swap0 after" << endl;
    cout << "a = " << *a << " " << "b =" << *b << endl;
    cout << "a = " << a << " " << "b =" << b << endl;
}

void my_swap2(int &a, int &b) {
    cout << "in my swap0 before" << endl;
    cout << "a = " << a << " " << "b =" << b << endl;
    cout << "a = " << &a << " " << "b =" << &b << endl;
    int tmp = a;
    a = b;
    b = tmp;
    cout << "in my swap0 after" << endl;
    cout << "a = " << a << " " << "b =" << b << endl;
    cout << "a = " << &a << " " << "b =" << &b << endl;
}

int* create_arr(int n) {
    return new int[n] {};
}

int my_arr[]{ 1,2,3,4,5 };

int& find(int val){
    for (int k = 0; k < 5; k++) {
        if (my_arr[k] == val) {
            return my_arr[k];
        }
    }
}

void test_swap() {
    //cout << hipotenuse(3, 4) << endl;
    //test_pointers();
    /*
    int a = 3;
    int b = 4;
    cout << "in main before" << endl;
    cout << "a = " << a << " " << "b =" << b << endl;
    cout << "a = " << &a << " " << "b =" << &b << endl;
    //my_swap1(&a, &b);
    my_swap2(a, b);
    cout << "in main after" << endl;
    cout << "a = " << a << " " << "b =" << b << endl;
    cout << "a = " << &a << " " << "b =" << &b << endl;
    int* arr = create_arr(5);
    for(int k =0; k < 5; ++k)
        cout << arr[k] << endl;
*/
}

void test_fun_pointers() {
    for (int k = 0; k < 5; ++k)
        cout << my_arr[k] << endl;
    find(2) = 15;
    for (int k = 0; k < 5; ++k)
        cout << my_arr[k] << endl;
    cout << endl;
    cout << *(my_arr + 1) << my_arr[1] << endl;
    cout << *create_arr << endl;
}

int sum(int a, int b) {
    cout << "Sum: ";
    return a + b;
}

int mul(int a, int b) {
    cout << "Mult: ";
    return a * b;
}

void function_pointers() {
    cout << sum << endl;
    cout << mul << endl;
    int (*pfun)(int, int) = sum; // это указатель на функцию
    cout << pfun(3, 4) << endl;
    pfun = mul;
    cout << pfun(3, 4) << endl;
    int((*pfun2[2])(int, int)) { mul, sum };
    cout << "Enter 0 - for mult calc" << endl;
    cout << "Enter 1 - for sum calc" << endl;
    int c;
    cin >> c;
    cout << pfun2[c](13, 15) << endl;
}

struct Point {
    int x = 0;
    int y = 0;
};

struct Line {
    Point pt1;
    Point pt2;
};

struct Man {
    const char* name;
    int age;
    const char* workplace;
    int salary;

    void show() {
        cout << name << "   "
            << age << "   "
            << workplace << "   "
            << salary << endl;
    }
};

void show(Man& man) {
    cout << man.name << "   "
         << man.age << "   "
         << man.workplace << "   "
         << man.salary << endl;
}

void show(Point &pt) {
    cout << "(" << pt.x << ", " << pt.y << ")" << endl;
}

double distance(Point& pt1, Point& pt2) {
    int dx = (pt1.x - pt2.x);
    int dy = (pt1.y - pt2.y);
    return sqrt(dx * dx + dy * dy);
}

void main() {
    Point pt1{0, 0};
    Point pt2{3, 4};
    //pt.x = 10;
    //pt.y = 11;
    Point arr_points[]{ pt1, pt2 };
    show(pt1);
    show(pt2);
    cout << distance(pt1, pt2) << endl;
    cout << distance(arr_points[0], arr_points[1]) << endl;


    Man man{ "Egor", 42, "Agent", 95000 };
    show(man);
    man.salary = 87000;
    show(man);
    man.show();

    struct Point2 {
        double d1;
        int d2;
    };

    Point2 pt3;

    cout << sizeof(pt1) << " " << sizeof(pt1.x) << endl;
    cout << sizeof(pt3) << " " << sizeof(pt3.d1) + sizeof(pt3.d2) << endl;

    pt1 > pt2;
}