private void examDetailsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            StudentExamStatus s = new StudentExamStatus();

            this.Hide();
            s.Show();
        }
        private void cmdBack(object sender, EventArgs e)
        {
            StudentExamStatus s = new StudentExamStatus();

            this.Hide();
            s.Show();
        }
        private void cmdLogin(object sender, EventArgs e)
        {
            //if(txtName.Text == "admin")
            //{
            //    //teacher
            //    ManageExam m = new ManageExam();
            //    this.Hide();
            //    m.Show();
            //}
            //else if(txtName.Text=="student")
            //{
            //    //student
            //    StudentExamStatus s = new StudentExamStatus();
            //    this.Hide();
            //    s.Show();
            //}
            bool isfound = false;

            foreach (UserClass u in ListClass.mylist)
            {
                if (txtName.Text == u.Username && txtPassword.Text == u.Password && u.Role == txtRole.Text)
                {
                    isfound          = true;
                    MyUtil.loginuser = u;
                }
            }
            if (isfound && txtRole.Text == "Teacher")
            {
                MessageBox.Show("Login successfully");
                txtName.Text     = "";
                txtPassword.Text = "";
                ManageExam m = new ManageExam();
                this.Hide();
                m.Show();
            }
            else if (isfound)
            {
                MessageBox.Show("Login successfully");
                txtName.Text     = "";
                txtPassword.Text = "";
                StudentExamStatus s = new StudentExamStatus();
                this.Hide();
                s.Show();
            }
            else
            {
                MessageBox.Show("Invalid username or password");
            }
        }