public MainPage()
        {
            this.InitializeComponent();

            this.NavigationCacheMode = NavigationCacheMode.Required;

            calcEngine = new CalcEngine();
            initialize();
        }
        public MainWindow()
        {
            InitializeComponent();

            displayResult = new DisplayResult() { ResultText = "0" };
            this.DataContext = displayResult;

            calculatorEngine = new CalcEngine();
        }
 public MainWindow()
 {
     InitializeComponent();
     engine = new CalcEngine();
     clearflag = true;
 }