vector of bits

#include <iostream>
#include <math.h>
#include <chrono>
using namespace std;
// --- --- --- --- ---
const short N = 16;
class set
{
    private: bool array[N];
    public:
        void is_empty()
        {
            bool flag = true;
            for(int i = 0; i < N; i++)
                if (this->array[i]==true) flag=false;
            cout << endl;
            if(flag) cout << "It's empty";
            else cout << "It isn't empty";
            cout<<endl;

        }
        // --- --- ---
        set() { for(int i = 0; i < N; i++) this->array[i] = false; };
        // --- --- ---
        void generating()
        {
            short size_tmp = rand() % N; // generates random size for one array
            short tmp;
            for(int i = 0; i < size_tmp; i++)
            {   tmp = rand() % N;
                if (this->array[tmp]==false) this->array[tmp]=true;
            }
        };
        // --- --- ---
        set operator || (const set& second) const{
            set third;
            for(int i = 0; i < N; i++)
                if((this->array[i] == true) || (second.array[i] == true)) third.array[i]=true;
            return third;
        }
        // --- --- ---
        set operator && (const set& second) const{
            set third;
            for(int i = 0; i < N; i++)
                if((array[i] == true) && (second.array[i] == true)) third.array[i]=true;
            return third;
        }
        // --- --- ---
    set  operator - (const set& second) const{
        set third;
        for(int i = 0; i < N; i++)
        if((array[i] == true) && (second.array[i] == false)) third.array[i]=true;
            return third;
    }
       // --- --- ---
        void print()
        {
            cout << "[ ";
            for(int i = 0; i < N; i++)
            {
                if (this->array[i]==true)
                    cout << hex << i << ' ';
            }
            cout << ']' << endl;
        }
};
// --- --- --- --- ---
int main()
{
    srand(2);
    set a, b, c, d, e, tmp;
    a.generating(); cout << "A: "; a.print();
    b.generating(); cout << "B: "; b.print();
    c.generating(); cout << "C: "; c.print();
    d.generating(); cout << "D: "; d.print();
    double result;
    cout << endl << "*Calculating result*" << endl;
    for(int i = 0; i < pow(10, 7); i++)
    {
        auto t1 = chrono::high_resolution_clock::now();
        e = ((a||c)-(b||d));
        auto t2 = chrono::high_resolution_clock::now();
        auto diff = chrono::duration_cast<chrono::duration<double>>(t2 - t1);
        result += diff.count();
    }
    cout << endl << "E: "; e.print();
    cout << "time: " << result << " seconds" << endl;
    return 0;
}
// --- --- --- --- --- --- --- --- ---