Массив структур students. Сортировка.

#include <iostream>
#include <iomanip>
#include <string>

using namespace std;

struct student {
public:
    student() : fullname(L"-"), group(L"-"), point(0) { };
    student(wstring _fullname, wstring _group, double _point) : fullname(_fullname), group(_group), point(_point) { };
    student(const student &);
    ~student();

    void input();
    void output()const;
    student operator =(const student &);
    friend bool operator==(const student &, const student &);
    friend bool operator!=(const student &, const student &);
    void check_double(const wstring);

    wstring fullname;
    wstring group;
    double point;
};

void ru();
void uswap(student &, student &);
void quick_sort(student *, const size_t, const size_t);

int main() {
    ru();
    student ivanov = student(L"Иванов Игорь Филиппович", L"115а", 4.12);
    student petrov = student(L"Петров Аркадий Егорович", L"114в", 4.27);
    student sidorova = student(L"Сидорова Наталья Петровна", L"119г", 4.81);

    if (ivanov == petrov) wcout << L"Иванов и Петров совпадают\n";
    if (petrov != sidorova) wcout << L"Петров и Сидорова не совпадают\n";

    const size_t size = 6;
    student students[size];
    students[0] = ivanov;
    students[1] = petrov;
    students[2] = sidorova;
    for (size_t n = 3; n < size; n++) students[n].input();

    wcout << L"\n\t\t\tИсходный список студентов:\n\n";
    for (size_t n = 0; n < size; n++) students[n].output();

    quick_sort(students, 0, size - 1);
    wcout << L"\n\t\t Отсортированный список студентов:\n\n";
    for (size_t n = 0; n < size; n++) students[n].output();

    wcout << L"\n\t\t\t Вывод пустого объекта:\n\n";
    student unknown;
    unknown.output();

    cin.get();
    return 0;
}

student::~student() {
    group = fullname = L"";
    point = 0;
}

student::student(const student & _student) {
    this->fullname = _student.fullname;
    this->group = _student.group;
    this->point = _student.point;
}

student student::operator=(const student & _student) {
    this->fullname = _student.fullname;
    this->group = _student.group;
    this->point = _student.point;
    return *this;
}

bool operator==(const student & _left, const student & _rigth) {
    bool flag;
    if (_left.fullname == _rigth.fullname && _left.group == _rigth.group && _left.point == _rigth.point) flag = true;
    else flag = false;
    return flag;
}

bool operator!=(const student & _left, const student & _rigth) {
    return !(_left == _rigth);
}

void student::input() {
    wcout << L"Введите ФИО студента: "; getline(wcin, fullname);
    wcout << L"Введите группу:       "; getline(wcin, group);
    check_double(L"Введите средний балл: ");
    system("cls");
}
void student::output()const {
    wchar_t v = L' ';
    streamsize accuracy = 2, fio = 48, grp = 8, pnt = 6;
    wcout << v << left  << setw(fio) << fullname
          << right << setw(grp) << group
          << right << setw(pnt) << fixed << setprecision(accuracy) << point << endl;
}

void student::check_double(const wstring _msg) {
    do {
        wcout << _msg; cin >> point;
        if (cin.good() && point >= 0 && point <= 5) break;
        else {
            cin.clear();
            cin.ignore(80,'\n');
            wcout << L"\aВы ошиблись!\n";
        }
    } while (true);
    fflush(stdin);
}

void quick_sort(student * _students, const size_t _beg, const size_t _end) {
    int n = (int)_beg, m = (int)_end;
    student mid;
    mid.fullname = _students[(_beg + _end) >> 1].fullname;

    do {
        while (_students[n].fullname  < mid.fullname  && n < (int)_end) ++n;
        while (_students[m].fullname  > mid.fullname  && m > (int)_beg) --m;

        if (n <= m) {
            if (n < m) uswap(_students[n], _students[m]);
            ++n;
            --m;
        }
    } while (n <= m);

    if ((int)_beg < m) quick_sort(_students, _beg, m);
    if (n < (int)_end) quick_sort(_students, n, _end);
}

void uswap(student & _a, student & _b) {
    student temp = _a;
    _a = _b;
    _b = temp;
}

void ru() {
    wcout.imbue(locale("rus_rus.866"));
    wcin.imbue(locale("rus_rus.866"));
}