Visual Basic is Microsoft's high-level object-oriented rapid application development environment for the Windows platform. The first versions of Visual Basic were intended to target Windows 3.0 (a version for DOS existed as well), however it was not until version 3.0 for Windows 3.1 that this programming language gained large-scale acceptance in the shareware and corporate programming community.
Using drawing tools that resemble those found in hardcopy page layout programs or PhotoShop, VB programmers make user interfaces by drawing controls and other UI components onto forms. The programmer then adds code to respond to user interactions with the controls (for example, clicks, drag and drop, etc) known as events. The code can trigger events in other controls (for example, by displaying text or an image), execute procedures (run some algorithm based on the values entered in some control, output data, do business logic, etc), or almost anything else one might do in code.
Visual Basic can be considered to be an interpreted language like its Basic ancestor, with appropriate modifications to accommodate object-oriented programming, and has implicit type conversion. That is, the VB development environment goes to great lengths to format (and aid the user in formatting) programming code so that it conforms to executable syntax. For example, VB will appropriately change the case of newly typed variable names to match those that have been declared previously (if they have been declared at all!). Traditionally, VB is known for compiling programs into pseudo-code (p-code, similar to Java's byte code) which is interpreted at runtime, requiring the use of dynamically-linked libraries (for example, VBRUN300.DLL for version 3 of Visual Basic, circa 1992) but newer versions can compile code into something more closely resembling the efficient machine code generated by C-like compilers. VB6 can be compile either into p-code or into native code; in fact VB6 uses the Microsoft C++ compiler to generate the executable.
For new Windows programmers, VB offers the advantage of being able to access much of the Windows UI functionality without knowing much about how it works by hiding the technical details. Although accessing low-level Windows UI functionality is possible, doing so in VB is as, or more difficult compared to such access using Visual C++ or other lower level programming languages. Recently VB.NET has gone a long way to fixing some of the limitations.
Using custom controls provided by Microsoft or third parties, almost any functionality that is possible in Windows can be added to a VB program by drawing a custom control onto a form in the project.
Visual Basic traditionally comes in at least entry level and professional versions, with various designations depending on Microsoft's contemporary marketing strategy. The different versions are generally differentiated by the number of custom controls included, and the capabilities of the compiler. Higher priced packages include more functionality.
Evolution of Visual Basic
VB 1.0 was introduced in 1991. The approach for connecting the programming language to the graphical user interface is derived from a system called Tripod (sometimes also known as Ruby), originally developed by Alan Cooper, which was further developed by Cooper and his associates under contract to Microsoft.
Timeline of Visual Basic
- Visual Basic 1.0 (May 1991) was released for Windows.
- Visual Basic 1.0 for DOS was released in September 1992. The language itself was not quite compatible with Visual Basic for Windows, as it was actually the next version of Microsoft's DOS-based BASIC compilers, Microsoft QuickBASIC compiler and the BASIC Professional Development System 7.1. The interface was barely graphical, using extended ASCII characters to simulate the appearance of a GUI.
- Visual Basic 2.0 was released in November 1992. The programming environment was easier to use, and its speed was improved.
- Visual Basic 3.0 was released in the summer of 1993 and came in Standard and Professional versions. VB3 included a database engine that could read and write Access databases.
- Visual Basic 4.0 (August 1995) was the first version that could create 32-bit as well as 16-bit Windows programs. It also introduced the ability to write classes in Visual Basic.
- With version 5.0 (February 1997), Microsoft released Visual Basic exclusively for 32-bit versions of Windows. Programmers who preferred to write 16-bit programs were able to import programs written in Visual Basic 4.0 to Visual Basic 5.0, and Visual Basic 5.0 programs can easily be converted with Visual Basic 4.0. Visual Basic 5.0 also introduced the ability to create custom user controls, as well as the ability to compile to native Windows executable code, speeding up runtime code execution.
- Visual Basic 6.0 (Mid 1998) improved in a number of areas, including the ability to create web-based applications using Internet Explorer. Visual Basic 6 is no longer supported.
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