public void addStudent(int kurs, int student)
        {
            DAO_Kurs      dao   = new DAO_Kurs();
            List <Kurs>   list  = dao.getKursy();
            List <string> ls    = list[kurs].students;
            bool          check = false;

            for (int i = 0; i < ls.Count; i++)
            {
                string[] enteries = ls[i].Split(',');
                if (enteries[0] == student.ToString())
                {
                    check = true;
                }
            }

            DAO_Student    dao_s    = new DAO_Student();
            List <Student> studenci = dao_s.getStudenci();

            for (int i = 0; i < studenci.Count; i++)
            {
                if (studenci[i].id == student)
                {
                    if (!check)
                    {
                        ls.Add(studenci[i].id.ToString() + "," + studenci[i].imie.ToString() + "," + studenci[i].nazwisko.ToString() + "," + studenci[i].indeks.ToString());
                    }
                }
            }
            list[kurs].students = ls;
            dao.setKursy(list);
        }
        public void addKurs(string name)
        {
            DAO_Kurs    dao   = new DAO_Kurs();
            List <Kurs> list  = dao.getKursy();
            int         index = list.Last().id;
            Kurs        nkurs = new Kurs(index + 1, name);

            list.Add(nkurs);
            dao.setKursy(list);
        }
        public void editKurs(int index, string name)
        {
            DAO_Kurs    dao  = new DAO_Kurs();
            List <Kurs> list = dao.getKursy();

            foreach (var k in list)
            {
                if (k.id == index)
                {
                    k.name = name;
                }
            }
            dao.setKursy(list);
        }
        public void deleteStudent(int kurs, int student)
        {
            DAO_Kurs      dao   = new DAO_Kurs();
            List <Kurs>   list  = dao.getKursy();
            List <string> ls    = list[kurs].students;
            bool          check = false;

            for (int i = 0; i < ls.Count; i++)
            {
                string[] enteries = ls[i].Split(',');
                if (enteries[0] == student.ToString())
                {
                    ls.RemoveAt(i);
                }
            }
            list[kurs].students = ls;
            dao.setKursy(list);
        }
        public void deleteKurs(int index)
        {
            DAO_Kurs    dao       = new DAO_Kurs();
            List <Kurs> list      = dao.getKursy();
            Kurs        to_delete = null;

            foreach (var k in list)
            {
                if (k.id == index)
                {
                    to_delete = k;
                }
            }
            if (to_delete != null)
            {
                list.Remove(to_delete);
            }
            dao.setKursy(list);
        }
        public List <string> getAllKursy()
        {
            DAO_Kurs dao = new DAO_Kurs();

            return(dao.getKursyString());
        }