Windows Versus DOS Programming

Windows Versus DOS Programming

A Windows program is quite different from its ancient relative, the MS-DOS program. A DOS program follows a relatively strict path from beginning to end. Although this does not necessarily limit the functionality of the program, it does limit the road the user has to take to get to it. A DOS program is like walking down a hallway; to get to the end you have to walk down the hallway, passing any obstacles that you may encounter. A DOS program would only let you open certain doors along your stroll. Windows, on the other hand, opened up the world of event-driven programming. Events in this context include, for example, clicking a button, resizing a window, or changing an entry in a text box. The code that you write responds to these events. To go back to the hallway analogy: In a Windows program, to get to the end of the hall, you just click on the end of the hall. The hallway can be ignored. If you get to the end and realize that is not where you wanted to be, you can just set off for the new destination without returning to your starting point. The program reacts to your movements and takes the necessary actions to complete your desired tasks (Visual Basic 2005).

Another big advantage in a Windows program is the abstraction of the hardware; which means that Windows takes care of communicating with the hardware for you. You do not need to know the inner workings of every laser printer on the market just to create output. You do not need to study the schematics for graphics

cards to write your game. Windows wraps up this functionality by providing generic routines that communicate with the drivers written by hardware manufacturers. This is probably the main reason that Windows has been so successful. The generic routines are referred to as the Windows Application Programming Interface (API). Before Visual Basic 1.0 was introduced to the world in 1991, developers had to be well versed in C and C++ programming, as well as the building blocks of the Windows system itself, the Windows API. This complexity meant that only dedicated and properly trained individuals were capable of turning out software that could run on Windows. Visual Basic changed all of that, and it has been estimated that there are now as many lines of production code written in Visual Basic as in any other language. Visual Basic changed the face of Windows programming by removing the complex burden of writing code for the user interface (UI). By allowing programmers to draw their own UI, it freed them to concentrate on the business problems they were trying to solve. Once the UI is drawn, the programmer can then add the code to react to events.

Visual Basic has also been extensible from the very beginning. Third-party vendors quickly saw the market for reusable modules to aid developers. These modules, or controls, were originally referred to as VBXs (named after their file extension). Prior to Visual Basic 5.0, if you did not like the way a button behaved, you could either buy or create your own, but those controls had to be written in C or C++. Database access utilities were some of the first controls available. Version 5 of Visual Basic introduced/The concept of ActiveX, which allowed developers to create their own ActiveX controls. When Microsoft introduced Visual Basic 3.0, the programming world changed again. Now you could build database applications directly accessible to users (so-called front-end applications) completely with Visual Basic. There was no need to rely on third-party controls. Microsoft accomplished this task with the introduction of Data Access Objects (DAO), which allowed programmers to manipulate data with the same ease as manipulating the user interface.

Versions 4.0 and 5.0 extended the capabilities of Version 3.0 to allow developers to target the new Windows 95 platform. Crucially they also made it easier for developers to write code, which could then be manipulated to make it usable to other language developers. Version 6.0 provided a new way to access databases with the integration of ActiveX Data Objects (ADO). The ADO feature was developed by Microsoft to aid Web developers using Active Server Pages to access databases. All of the improvements to Visual Basic over the years have ensured its dominant place in the programming world. It helps developers write robust and maintainable applications in record time. With the release of Visual Basic .NET in February 2002, most of the restrictions that used to exist have been obliterated. In the past, Visual Basic has been criticized and maligned as a “toy” language, as it did not provide all of the features of more sophisticated languages such as C++ and Java. Now, Microsoft has removed these restrictions and made Visual Basic .NET a very powerful development tool. This trend continues with Visual Basic 2005. Although not as drastic a change as from Visual Basic 6 to Visual Basic .NET, there are enough improvements in the language and integrated development environment that Visual Basic 2005 is a welcome upgrade and is a great choice for programmers of all levels.