private bool DoesThisStudent(Student aStudent)
 {
     foreach (Student student in studentList)
     {
         if (aStudent.RegNo == student.RegNo)
             return true;
     }
     return false;
 }
 public bool CheckRegNo(Student aStudent)
 {
     if (DoesThisStudent(aStudent))
     {
         return true;
     }
     else
     {
        return  false;
     }
 }
 public bool checkRegNo(Department aDeparment,Student aStudent)
 {
     bool check = false;
       foreach(Department department in departmentList)
       {
           check = department.CheckRegNo(aStudent);
           if (check)
               return true;
       }
       return check;
 }
 public bool AddStudent(Department aDepartment, Student aStudent)
 {
     bool check=false;
     foreach (Department department in departmentList)
     {
         if (department.Code == aDepartment.Code)
         {
            check=aDepartment.AddStudent(aStudent);
         }
     }
     return check;
 }
        private void studentSaveButton_Click(object sender, EventArgs e)
        {
            aStudent = new Student();
            aStudent.RegNo = studentRegNoTextBox.Text;
            aStudent.Name = studentNameTextBox.Text;
            aStudent.Email = studentEmailTextBox.Text;

            aDepartment=new Department();
            aDepartment = (Department)departmentSaveComboBox.SelectedItem;

            bool check = aUniversity.checkRegNo(aDepartment, aStudent);

            if (check)
            {
                MessageBox.Show("This Registration No already exists.");
            }
            else
            {
                aUniversity.AddStudent(aDepartment, aStudent);
                MessageBox.Show("Student added.");
            }
        }
 //public bool AddStudent(Student aStudent)
 //{
 //  if(DoesThisStudent(aStudent))
 //  {
 //      return true;
 //  }
 //  else
 //  {
 //      studentList.Add(aStudent);
 //      return false;
 //  }
 //}
 public bool AddStudent(Student aStudent)
 {
     studentList.Add(aStudent);
     return true;
 }