private void login_process()
        {
            string Email      = email.Text.ToLower();
            string Pass       = pass.Text;
            user   LoggedUser = classRoom.signIn(Email, Pass);

            if (LoggedUser.user_kind == "1")
            {
                if (LoggedUser.user_type == 1)
                {
                    InstMainPage main = new InstMainPage(LoggedUser);
                    this.Hide();
                    main.Show();
                }
                else if (LoggedUser.user_type == 2)
                {
                    StdMainPage main = new StdMainPage(LoggedUser);
                    this.Hide();
                    main.Show();
                }
            }
            else if (LoggedUser.user_kind == "-2")
            {
                MessageBox.Show("Sorry the Password is not Correct :(", "LogIn", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            else
            {
                MessageBox.Show("Sorry this Email is not Exist, Please Register and Login again :(", "LogIn", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
 private void back_mainpage_Click(object sender, EventArgs e)
 {
     if (user_loggedin.user_type == 1)
     {
         InstMainPage main = new InstMainPage(user_loggedin);
         this.Hide();
         main.ShowDialog();
     }
     else
     {
         StdMainPage main = new StdMainPage(user_loggedin);
         this.Hide();
         main.ShowDialog();
     }
 }