private void buttonAdd_Click(object sender, EventArgs e)
 {
     try
     {
         Course c = new Course();
         c.courseName = textBoxCourseName.Text;
         c.cId        = Int32.Parse(comboBoxClaasId.Text);
         bool b = AdminController.AddCourse(c);
         if (b)
         {
             MessageBox.Show("Courses Added");
             this.Close();
         }
         else
         {
             MessageBox.Show("Failed");
         }
     }
     catch (Exception)
     {
         MessageBox.Show("Invalid input");
     }
 }