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// studenti.h -- defining a Student class using private inheritance
#ifndef STUDENTC_H_
#define STUDENTC_H_
#include <iostream>
#include <valarray>
#include <string>
class Student : private std::string, private std::valarray<double>
{
private:
    typedef std::valarray<double> ArrayDb;
    // private method for scores output
    std::ostream & arr_out(std::ostream & os) const;
public:
    Student() : std::string("Null Student"), ArrayDb() {}
    explicit Student(const std::string & s)
    : std::string(s), ArrayDb() {}
    explicit Student(int n) : std::string("Nully"), ArrayDb(n) {}
    Student(const std::string & s, int n)
    : std::string(s), ArrayDb(n) {}
    Student(const std::string & s, const ArrayDb & a)
    : std::string(s), ArrayDb(a) {}
    Student(const char * str, const double * pd, int n)
    : std::string(str), ArrayDb(pd, n) {}
    ~Student() {}
    double Average() const;
    double & operator[](int i);
    double operator[](int i) const;
    const std::string & Name() const;
// friends
    // input
    friend std::istream & operator>>(std::istream & is,
    Student & stu); // 1 word
    friend std::istream & getline(std::istream & is,
    Student & stu); // 1 line
    // output
    friend std::ostream & operator<<(std::ostream & os,
    const Student & stu);
};
#endif

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// studenti.cpp -- Student class using private inheritance
#include "studenti.h"
using std::ostream;
using std::endl;
using std::istream;
using std::string;
// public methods
double Student::Average() const
{
    if (ArrayDb::size() > 0)
        return ArrayDb::sum()/ArrayDb::size();
    else
        return 0;
}
const string & Student::Name() const
{
    return (const string &) *this;
}
double & Student::operator[](int i)
{
    return ArrayDb::operator[](i); // use ArrayDb::operator[]()
}
double Student::operator[](int i) const
{
    return ArrayDb::operator[](i);
}
// private method
ostream & Student::arr_out(ostream & os) const
{
    int i;
    int lim = ArrayDb::size();
    if (lim > 0)
    {
        for (i = 0; i < lim; i++)
        {
            os << ArrayDb::operator[](i) << " ";
            if (i % 5 == 4)
                os << endl;
        }
        if (i % 5 != 0)
            os << endl;
    }
    else
        os << " empty array ";
    return os;
}
// friends
// use String version of operator>>()
istream & operator>>(istream & is, Student & stu)
{
    is >> (string &)stu;
    return is;
}
// use string friend getline(ostream &, const string &)
istream & getline(istream & is, Student & stu)
{
    getline(is, (string &)stu);
    return is;
}
// use string version of operator<<()
ostream & operator<<(ostream & os, const Student & stu)
{
    os << "Scores for " << (const string &) stu << ":\n";
    stu.arr_out(os); // use private method for scores
    return os;
}