Download 'calc.zip' Another example is a visual version of the simple expression calculator. In this example the expression is keyed into a data entry field. A button is clicked to produce the result. Although the grammar which is the basis for the program differs in only a few lines, the program is much larger than the simple expression calculator console application. This is due solely to the extra code required by Delphi for a visual look and feel.
Error handling is via a message to the screen.
The download is 174 kb. The executable 'CHD3GUI.exe', which you can run and play around with. Download 'calcgui.zip' Another example is the simple expression calculator as a component. In this example a component has been made which can be used in either design time or runtime modes. The component has these new events, methods and properties.