Функции.Динамичесские массивы и структуры

#include <iostream>
#include <iomanip>
#include <time.h>
#include <math.h>
#include <vector>
#include <algorithm>
#include <string>
 
const std::string grade_names[4][3] = 
        {
            {"math", "physics", "history"},
            {"math", "physics", "drawing"},
            {"math", "physics", "programming"},
            {"math", "language", "programming"},
        };
 
std::string namegen(bool patronymic=false, bool surname=false)
{
    std::string prefix[] = {"Po", "De", "Ki", "Mo", "Zi", "Ni", "Di", "Li", "To", "Ba"};
    std::string syllable[] = {"sem", "grom", "grim", "grem", "bol", "bil", "le", "til", "an", "ro"};
    std::string suffix[] = {"ko", "kov", "in", "ed","ov", "iko", "ako", "onko", "enko", "dor"};
    std::string aname = prefix[rand()%10]+syllable[(rand()%10)];
    if (surname)
        aname += syllable[rand()%10] + suffix[rand()%10];
    if (patronymic)
        aname += "ovich";
    return aname;
}
 
typedef struct
{
    std::string name;
    std::string patronymic;
    std::string surname;
    int year;
    int group;
    std::vector<std::vector<int>> grades;
} student;
 
void fill_student(student& stud, int year, int group)
{
    if (stud.name=="")
    {
        stud.name = namegen();
        stud.patronymic = namegen(true);
        stud.surname = namegen(false, true);
    }
    stud.year = year;
    stud.group = group;
    stud.grades.resize(4, std::vector<int>(3, 0));
    for (int i=0; i<4; i++)
        for (int j=0; j<3; j++)
            stud.grades[i][j] = rand()%4+2;
}
 
void print_student(student a_student)
{
    std::cout << " * " << a_student.name << " " 
        << a_student.patronymic << " " << a_student.surname << ", " 
        << a_student.year << "-" << a_student.group << std::endl;
    for (int i=0; i<4; i++)
    {
        for (int j=0; j<3; j++)
            std::cout << std::setw(15) << grade_names[i][j] << ": " << a_student.grades[i][j];
        std::cout << std::endl;
    }
}
 
int main()
{
    srand(time(0));
 
    std::vector<student> students;
 
    for (int group=1; group<3; group++)
        for (int i=0; i<5; i++)
        {
            student a_student;
            for (int year=2009; year<2011; year++) 
            {
                fill_student(a_student, year, group);
                students.push_back(a_student);
                print_student(a_student);
            }
        }
    system("pause");
    return 0;
}