Закрытое наследование

#ifndef WINE_H
#define WINE_H
#include <valarray>
#include <string>
#include <iostream>
 
using std::cout;
using std::cin;
using std::endl;
 
class Pair:private std::valarray<int>
{
private:
    typedef std::valarray<int>ArrayYears;
    typedef std::valarray<int>ArrayBottles;
    int num;
public:
    Pair(){}
    int&operator [](int i);
    int operator[](int i)const;
    Pair(int a):ArrayYears(a),num(a){}
    Pair(int n, int Ye[], int Bt[]):ArrayYears(n),num(n)
    {
        for(int i = 0; i < num; i++){
            ArrayYears::operator [](i) = Ye[i];
            ArrayBottles::operator [](i) = Bt[i];
        }
    }
    void show();
    void getBottles();
    int sum();
};
 
 
class Wine:private Pair, private std::string
{
private:
    typedef Pair date_and_bottles;
public:
    Wine(const char*a, int b):std::string(a),date_and_bottles(b) {}
    void getBottles();
    void show();
    Wine(const char*i, int n, int a[], int b[]):std::string(i), date_and_bottles(n,a,b){}
    std::string&lable();
    int sum();
};
 
#endif // WINE_H

#include "wine.h"
 
int &Pair::operator [](int i)
{
    return ArrayYears::operator [](i),ArrayBottles::operator [](i);
}
 
int Pair::operator[](int i) const
{
    return ArrayBottles::operator [](i), ArrayYears::operator [](i);
}
 
void Pair::show()
{
 
    cout << "\n\tYear\tBottles" << endl;
    for (int i = 0; i < num; i++) {
        cout << "\t" << ArrayYears::operator [](i);
        cout << "\t" << ArrayBottles::operator [](i) << endl;
    }
}
 
void Pair::getBottles()
{
    for (int i = 0; i < num; i++) {
        cout << "Enter year: ";
        cin >> ArrayYears::operator [](i);
        cout << "Enter bottles for that year: ";
        cin >> ArrayBottles::operator [](i);
    }
}
 
int Pair::sum()
{
    int sum = 0;
    for (int i = 0; i < num; i++) {
        sum = ArrayBottles::sum();
    }
    return sum;
}
 
void Wine::getBottles()
{
    date_and_bottles::getBottles();
}
 
void Wine::show()
{
    cout << "Wine: " << (const std::string&)*this;
    date_and_bottles::show();
}
 
std::string &Wine::lable()
{
    return (std::string&)*this;
}
 
int Wine::sum()
{
    return date_and_bottles::sum();
}

#include <iostream>
#include "wine.h"
using namespace std;
 
int main() {
    setlocale(LC_ALL,"Russian");
 
 
    cout << "Enter name of wine: "; 
    char lab[50];
    cin.getline(lab, 50);
    cout << "Enter number of years: "; 
    int yrs;
    cin >> yrs;
    Wine holding(lab, yrs); 
    holding.getBottles(); 
    holding.show(); 
 
    const int YRS = 3;
    int y[YRS] = {1993, 1995, 1998};
    int b[YRS] = { 48, 60, 72};
    Wine more("Gushing Grape Red",YRS, y, b) ;
    more.show();
    cout << "Total bottles for " << more.lable() 
    << ": " << more.sum() << endl; 
    cout << "Bye\n";
 
 
    cout << "\nDone!\n\n";
}

return ArrayYears::operator [](i),ArrayBottles::operator [](i);