public static void Main(string[] args)
        {
            /* Testing the Student class */
            Student[] stds = new Student[7];
            stds[0] = new Student();
            stds[1] = new Student("s1", "57001");
            stds[2] = new Student("s2", "57002", 1994);
            stds[3] = new Student("s3", "57003", 1996);
            stds[4] = new Student("s4", "57004");
            stds[5] = new Student("s5", "57005", 1993);
            stds[6] = new Student("s6", "57006");

            Console.WriteLine("\n--- Initial Students' state ---");
            foreach (Student s in stds)
                Console.WriteLine(s);

            Console.WriteLine("\n--- Playing with s4, s5, s6 objects ---");
            stds[4].Name = "Mario";
            stds[5].YearOfBirth = 1900;
            stds[6].isActive = false;
            for (int i = 4; i < stds.Length; i++)
                Console.WriteLine(stds[i]);

            Console.ReadKey();
        }