Significant Language Features
Visual Basic is not only a programming language, but
also a complete graphical development environment. This environment allows users with little programming experience to quickly
develop useful Microsoft Windows applications which have the ability to use OLE ( Object Linking and Embedding ) objects,
such as an Excel spreadsheet. Visual Basic also has the ability to develop programs that can be used as a front end application
to a database system, serving as the user interface which collects user input and displays formatted output in a more appealing
and useful form than many SQL versions are capable of.
Visual Basic's main selling point is the ease with which it allows the user to create nice looking, graphical
programs with little coding by the programmer, unlike many other languages that may take hundreds of lines of programmer keyed
code. As the programmer works in the graphical environment, much of the program code is automatically generated by the Visual
Basic program. In order to understand how this happens it is necessary to understand the major concepts, objects and tools
used by Visual Basic. The main object in Visual Basic is called a form. When you open a new project, you will start with a
clear form that looks similar to this :
This form will eventually be incorporated into your program
as a window. To this form you add controls. Controls are things like text boxes, check boxes and command buttons. Controls
are added to your form by choosing them from the Visual Basic "tool box" with the mouse and inserting them in the form. Yours
may look different, but the basic Visual Basic Tool Box looks like this :
example of a pOnce forms/controls are created, you can change
the properties ( appearance, structure etc. ) related to those objects in
that particular objects properties window. From this window, you choose the property you want to change from the list
and change its corresponding setting. Here is an properties window :
Finally, you can add events to your controls. Events are responses to actions performed
on controls. For example, in the "Hello world" program sample on this page, when you click on the command button on our form
the event that is triggered is the output of the message "Hello world" to the screen. Code must be written to create an event.
You can do this in Visual Basic's code window. Yours will look similar to this ( except of course, the body of the
sub-procedure where the actions are specified) :
Once the code box is open, you select the object to create an event for and the triggering action
( such as a certain mouse action ) from the drop down menus in the code box. You can open a code box for a particular form
by choosing it from the project window and selecting the View Code button. The project window contains a list
of objects associated with that project. Below is an example of a project window :
Once all your objects are created, you can combine them to form a single executable program that
can be run outside of the Visual Basic environment, in Microsoft Windows.
