Vector3D

// ConsoleApplication1.cpp : Defines the entry point for the console application.
//

#include <iostream>

#include "windows.h"

#include <string>


using namespace std;


class v3d {
public:
    double* arr;

    v3d() {
        cout << "Tworzymy..." << endl;
        arr = (double*)calloc(3, sizeof(double));
    }

    ~v3d() {
        cout << "Przed free: ";
        free(arr);
        cout << " i po free." << endl;
    }

    v3d operator + (const v3d& b)
    {
        v3d temp1;
        temp1.arr[0] = arr[0] + b.arr[0];
        temp1.arr[1] = arr[1] + b.arr[1];
        temp1.arr[2] = arr[2] + b.arr[2];
        return temp1;
    }

    v3d& operator += (const v3d& b)
    {
        arr[0] += b.arr[0];
        arr[1] += b.arr[1];
        arr[2] += b.arr[2];
        return *this;
    }
    v3d& operator -= (const v3d& b)
    {
        arr[0] -= b.arr[0];
        arr[1] -= b.arr[1];
        arr[2] -= b.arr[2];
        return *this;
    }

    v3d& operator = (const v3d& b)
    {
        this->arr[0] = b.arr[0];
        this->arr[1] = b.arr[1];
        this->arr[2] = b.arr[2];
        return *this;
    }

    double len() {
        return pow(pow(arr[0], 2) + pow(arr[1], 2) + pow(arr[2], 2), 0.5);
    }

    string to_str() {

        return "[" + to_string(arr[0]) + ", " + to_string(arr[1]) + ", " + to_string(arr[2]) + "]";
    }
};


int main()
{
    v3d a, b, sum;

    a.arr[0] = 12;
    a.arr[1] = -56;
    a.arr[2] = 5e-3;

    b.arr[0] = 7 - 3e2;
    b.arr[1] = 24.789;
    b.arr[2] = 0;

    a -= b;

    sum = a + b;

    cout << sum.to_str() << endl << sum.len() << endl;
    system("pause");
    return 0;
}