private void button1_Click(object sender, EventArgs e) { if (!string.IsNullOrEmpty(this.tb_user.Text)) { Game game = new Game(); game.answer = game.CreateNumbers(); List<int> userAnswer = game.ConvertStringToNumbers(this.tb_user.Text); this.label_npc.Text = game.ConvertNumbersToString(game.answer); game.GetResult(userAnswer); this.label_ans.Text = game.show_ans; } else { MessageBox.Show("Please Enter Number first!"); this.tb_user.Focus(); } }