private void btnCalculate_Click(object sender, RoutedEventArgs e) { try { double resultWindowArea, resultFrameSphere, resultFrameArea, windowWidht, windowHeight, frameWidht; // Default value of 0 is used if tryparse fails double.TryParse(txtWindowWidht.Text, out windowWidht); double.TryParse(txtWindowHeight.Text, out windowHeight); double.TryParse(txtFrameWidht.Text, out frameWidht); // Calculate results resultWindowArea = BusinessLogicWindow.CalculateWindowArea(windowWidht, windowHeight); resultFrameSphere = BusinessLogicWindow.CalculateFrameSphere(windowWidht, windowHeight); resultFrameArea = BusinessLogicWindow.CalculateFrameArea(windowWidht, windowHeight, frameWidht); // Show results txtWindowArea.Text = resultWindowArea.ToString(); txtFrameSphere.Text = resultFrameSphere.ToString(); txtFrameArea.Text = resultFrameArea.ToString(); } catch (Exception ex) { MessageBox.Show(ex.Message); } }