#include <iostream>
#include <cmath>
using namespace std;

class vector
{
private:

    int *mass;
    int size;
public:

vector(int *array, int n)
{
    size = n;
    mass = new int[size];
    for (int i = 0; i < size; i++)
    {
        mass[i] = array[i];
    }
}

int sum(vector B, int rez)
{

    for (int i = 0; i < size; i=i+2)
    {
        rez = B.mass[i] + B.mass[i+1]+rez;
    }

    return rez;

}


int vichitanie(vector B, int rez)
{
    rez = 0;
    for (int i = 0; i < size; i = i + 2)
    {
        rez = (B.mass[i+1] - B.mass[i])+rez;
    }

    return  rez;


}

int multiple(vector B, int k, int rez)
{
    rez = 0;
    for (int i = 0; i < size; i++)
    {
        rez = (B.mass[i] * k)+rez;
    }

    return rez;

}

int modul(vector B, int rez)
{
    rez = 0;
    for (int i = 0; i < size; i++)
    {
        rez = pow(B.mass[i],2)+rez;
    }

    return rez;
}


    ~vector()
    {
        cout << "Деструктор сработал" << endl;
    }
};

int main()
{
setlocale(LC_ALL, "rus");
int mass2[8];

for (int i = 0; i<8; i++)
{
    int p;
    cout << "Введите для 1 вектора " << i + 1 << " значение" << endl;
    cin >> p;
    mass2[i] = p;
}

int k, r = 0;
cout << "Введите коеф." << endl;
cin >> k;

vector obj1(mass2, 8);
//vector obj2(mass2, 8);

obj1.sum(obj1,r);
cout << "Сумма двух векторов = " << obj1.sum(obj1, r) << endl;

obj1.vichitanie(obj1, r);
cout << "Разность двух векторов = " << obj1.vichitanie(obj1, r) << endl;

obj1.multiple(obj1, k, r);
cout << "Умножение на коеф  = " << obj1.multiple(obj1, k, r) << endl;

obj1.modul(obj1,r);
cout << "Модуль вектора = " << obj1.modul(obj1, r) << endl;


system("pause");

return 0;

}

obj1.sum(obj1,r);
         ^^^^
cout << "Сумма двух векторов = " << obj1.sum(obj1, r) << endl;
                                             ^^^^

int sum(vector B, int rez)
        ^^^^^^^^
{

    for (int i = 0; i < size; i=i+2)
    {
        rez = B.mass[i] + B.mass[i+1]+rez;
    }

    return rez;

}

delete [] mass;

rez = B.mass[i] + B.mass[i+1]+rez;
                         ^^^