Visual Basic .NET
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|It has been suggested that this article or section be merged into Visual Basic. (Discuss)|
|File:Vb dot net.png|
|Usual file extensions||.vb|
|Paradigm||structured, imperative, object-oriented, declarative|
|Appeared in||2001 (last revised 2008)|
|Stable release||Visual Basic 2008 (VB 9.0) (November 19, 2007)|
|Typing discipline||dynamic, strong, both safe and unsafe, nominative|
|Major implementations||.NET Framework, Mono|
|Dialects||Microsoft Visual Studio .NET, .NET 2003, 2005, 2008,2010(Beta)|
|Website||Microsoft's VB.NET website|
Visual Basic .NET (VB.NET) is an object-oriented computer programming language that can be viewed as an evolution of Microsoft's Visual Basic (VB) which is generally implemented on the Microsoft .NET Framework. Microsoft currently supplies Visual Basic free of charge.
Versions of Visual Basic .NET
As of November 2007, there are four versions of Visual Basic .NET that were implemented by The Visual Basic Team
Visual Basic .NET (VB 7)
The original Visual Basic .NET was released alongside Visual C# and ASP.NET in 2002. Significant changes broke backward compatibility with older versions and caused a rift within the developer community.
Visual Basic .NET 2003 (VB 7.1)
Visual Basic .NET 2003 was released with version 1.1 of the .NET Framework. New features included support for the .NET Compact Framework and a better VB upgrade wizard. Improvements were also made to the performance and reliability of the .NET IDE (particularly the background compiler) and runtime. In addition, Visual Basic .NET 2003 was available in the Visual Studio .NET 2003 Academic Edition (VS03AE). VS03AE is distributed to a certain number of scholars from each country without cost.
Visual Basic 2005 (VB 8.0)
Visual Basic 2005 is the name used to refer to the update to Visual Basic .NET, Microsoft having decided to drop the .NET portion of the title.
For this release, Microsoft added many features, including:
- Edit and Continue
- Design-time expression evaluation.
- The My pseudo-namespace (overview, details), which provides:
- easy access to certain areas of the .NET Framework that otherwise require significant code to access
- dynamically-generated classes (notably My.Forms)
- Improvements to the VB-to-VB.NET converter 
- The Using keyword, simplifying the use of objects that require the Dispose pattern to free resources
- Just My Code, which hides boilerplate code written by the Visual Studio .NET IDE
- Data Source binding, easing database client/server development
Visual Basic 2005 introduced features meant to fill in the gaps between itself and other "more powerful" .NET languages, adding:
- .NET 2.0 languages features such as:
- XML comments that can be processed by tools like NDoc to produce "automatic" documentation
- Operator overloading 
- Support for unsigned integer data types commonly used in other languages
'IsNot' operator patented
One other feature of Visual Basic 2005 is the
IsNot operator that makes
'If X IsNot Y' equivalent to
'If Not X Is Y', which gained notoriety when it was found to be the subject of a Microsoft patent application.
Visual Basic 2005 Express
Part of the Visual Studio product range, Microsoft created a set of free development environments for hobbyists and novices, the Visual Studio 2005 Express series. One edition in the series is Visual Basic 2005 Express Edition, which was succeeded by Visual Basic 2008 Express Edition in the 2008 edition of Visual Studio Express.
The Express Editions are targeted specifically for people learning a language. They have a streamlined version of the user interface, and lack more advanced features of the standard versions. On the other hand, Visual Basic 2005 Express Edition does contain the Visual Basic 6.0 converter, so it is a way to evaluate feasibility of conversion from older versions of Visual Basic.
Visual Basic 2008 (VB 9.0)
Visual Basic 9.0 was released together with the Microsoft .NET Framework 3.5 on November 19, 2007.
For this release, Microsoft added many features, including:
- A true conditional operator If (boolean, value, value) to replace the IIF function.
- Anonymous types
- Support for LINQ
- Lambda expressions
- XML Literals
- Type Inference
- Extension methods
Visual Basic 'VBx' (VB 10.0)
In 2007, Microsoft planned to use the Dynamic Language Runtime (DLR) for the upcoming Visual Basic 10, also known as VBx. However, as of August 2009, no further mention of VBx working on the DLR has been made by Microsoft on development updates. Similar to C#, Visual Basic will be able to access objects from dynamic languages built on the DLR such as IronPython and IronRuby
Relation to older versions of Visual Basic (VB6 and previous)
Whether Visual Basic .NET should be considered as just another version of Visual Basic or a completely different language is a topic of debate. This is not obvious, as once the methods that have been moved around and that can be automatically converted are accounted for, the basic syntax of the language has not seen many "breaking" changes, just additions to support new features like structured exception handling and short-circuited expressions. Two important data type changes occurred with the move to VB.NET. Compared to VB6, the
Integer data type has been doubled in length from 16 bits to 32 bits, and the
Long data type has been doubled in length from 32 bits to 64 bits. This is true for all versions of VB.NET. A 16-bit integer in all versions of VB.NET is now known as a
Short. Similarly, the Windows Forms GUI editor is very similar in style and function to the Visual Basic form editor.
The version numbers used for the new Visual Basic (7, 7.1, 8, 9, ...) clearly imply that it is viewed by Microsoft as still essentially the same product as the old Visual Basic.
The things that have changed significantly are the semantics—from those of an object-based programming language running on a deterministic, reference-counted engine based on COM to a fully object-oriented language backed by the .NET Framework, which consists of a combination of the Common Language Runtime (a virtual machine using generational garbage collection and a just-in-time compilation engine) and a far larger class library. The increased breadth of the latter is also a problem that VB developers have to deal with when coming to the language, although this is somewhat addressed by the My feature in Visual Studio 2005.
The changes have altered many underlying assumptions about the "right" thing to do with respect to performance and maintainability. Some functions and libraries no longer exist; others are available, but not as efficient as the "native" .NET alternatives. Even if they compile, most converted VB6 applications will require some level of refactoring to take full advantage of the new language. Documentation is available to cover changes in the syntax, debugging applications, deployment and terminology.
The following simple example demonstrates similarity in syntax between VB and VB.NET. Both examples pop up a message box saying "Hello, World" with an OK button.
Classic VB example:
Private Sub Command1_Click() MsgBox "Hello, World" End Sub
A VB.NET example, MsgBox or the MessageBox class can be used:
Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click MsgBox("Hello, World") End Sub End Class
Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click MessageBox.Show("Hello, World") End Sub End Class
- Both Visual Basic 6 and Visual Basic .NET will automatically generate the
End Substatements when the corresponding button is clicked in design view. Visual Basic .NET will also generate the necessary
End Classstatements. The developer need only add the statement to display the "Hello, World" message box.
- Note that all procedure calls must be made with parentheses in VB.NET, whereas in VB6 there were different conventions for functions (parentheses required) and subs (no parentheses allowed, unless called using the keyword
- Also note that the names
Button1are not obligatory. However, these are default names for a command button in VB6 and VB.NET respectively.
- In VB.NET, the
Handleskeyword is used to make the sub
Button1_Clicka handler for the
Clickevent of the object
Button1. In VB6, event handler subs must have a specific name consisting of the object's name ("Command1"), an underscore ("_"), and the event's name ("Click", hence "Command1_Click").
- There is a function called
Microsoft.VisualBasicnamespace which can be used similarly to the corresponding function in VB6. There is a controversy about which function to use as a best practice (not only restricted to showing message boxes but also regarding other features of the
Microsoft.VisualBasicnamespace). Some programmers prefer to do things "the .NET way", since the Framework classes have more features and are less language-specific. Others argue that using language-specific features makes code more readable (for example, using
Integer(VB.NET) instead of
- In VB 2008, the inclusion of "Byval sender as Object, Byval e as EventArgs" has become optional.
The following example demonstrates a difference between VB6 and VB.NET. Both examples close the active window.
Classic VB Example:
Sub cmdClose_Click() Unload Me End Sub
A VB.NET example:
Sub btnClose_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnClose.Click Me.Close() End Sub
Note the 'cmd' prefix being replaced with the 'btn' prefix, conforming to the new convention previously mentioned.
Visual Basic 6 did not provide common operator shortcuts. The following are equivalent:
Sub Timer1_Timer() Me.Height = Me.Height - 1 End Sub
Sub Timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles Timer1.Tick Me.Height -= 1 End Sub
Long-time Visual Basic users have complained  about Visual Basic .NET because initial versions dropped a large number of language constructs and user interface features  that were available in VB6 (which is no longer sold by Microsoft now), and changed the semantics of those that remained; for example, in VB.NET parameters are (by default) passed by value, not by reference. Detractors refer pejoratively to VB.NET as Visual Fred or DOTNOT. On March 8, 2005, a petition  was set up in response to Microsoft's refusal to extend its mainstream support for VB6.
VB.NET's supporters state that the new language is in most respects more powerful than the original, incorporating modern object oriented programming paradigms in a more natural, coherent and complete manner than was possible with earlier versions. Opponents tend to respond that although VB6 has flaws in its object model, the cost in terms of redevelopment effort is too high for any benefits that might be gained by converting to VB.NET.
It is simpler to decompile languages that target Common Intermediate Language (CIL), including VB.NET, compared to languages that compile to machine code. Tools such as .NET Reflector can provide a close approximation to the original code due to the large amount of metadata provided in CIL.
Microsoft supplies an automated VB6-to-VB.NET converter with Visual Studio .NET, which has improved over time, but it cannot convert all code, and almost all non-trivial programs will need some manual effort to compile. Most will need a significant level of code refactoring to work optimally. Visual Basic programs that are mainly algorithmic in nature can be migrated with few difficulties; those that rely heavily on such features as database support, graphics, unmanaged operations or on implementation details are more troublesome.
In addition, the required runtime libraries for VB6 programs are provided with Windows 98 SE and above, while VB.NET programs require the installation of the significantly larger .NET Framework. The framework is included with Windows 7, Windows Vista, Windows XP Media Center Edition, Windows XP Tablet PC Edition, Windows Server 2008 and Windows Server 2003. For other supported operating systems such as Windows 2000 or Windows XP (Home or Professional Editions), it must be separately installed.
Microsoft's response to developer dissatisfaction has focused around making it easier to move new development and shift existing codebases from VB6 to VB.NET. Their latest offering is the VBRun website, which offers code samples and articles for:
- Using VB.NET to complete tasks that were common in VB6, like creating a print preview
- Integrating VB6 and VB.NET solutions (dubbed VB Fusion)
Cross-platform and open-source development
The creation of open-source tools for VB.NET development have been slow compared to C#, although the Mono development platform provides an implementation of VB.NET-specific libraries and a VB.NET 8.0 compatible compiler written in VB.NET, as well as standard framework libraries such as Windows Forms GUI library.
Hello world example
The following is a very simple VB.NET program, a version of the classic "Hello world" example created as a console application:
Module Module1 Sub Main() Console.WriteLine("Hello, world!") End Sub End Module
The effect is to write the text Hello, world! to the command line. Each line serves a specific purpose, as follows:
This is a module definition, a division of code similar to a class, although modules can contain classes. Modules serve as containers of code that can be referenced from other parts of a program.
It is common practice for a module and the code file, which contains it, to have the same name; however, this is not required, as a single code file may contain more than one module and/or class definition.
This is the entry point where the program begins execution. Sub is an abbreviation of "subroutine."
This line performs the actual task of writing the output. Console is a system object, representing a command-line console and granting programmatic access to the operating system's standard streams. The program calls the Console method WriteLine, which causes the string passed to it to be displayed on the console. Another common method is using MsgBox (a Message Box).
Option Strictcan be used to switch between safe and unsafe type checking.
- ↑ "Petition to Microsoft". Classicvb.org. 8 March 2005. http://www.classicvb.org/petition/. Retrieved 16 June 2009.
- ↑ What's New with the Visual Basic Upgrade Wizard in Visual Basic 2005
- ↑ Defining and Using Generics in Visual Basic 2005
- ↑ Operator Overloading in Visual Basic 2005
- ↑ Sherriff, Lucy (22 February 2005). "Real Software slams MS IsNot patent application". The Register. http://www.theregister.co.uk/2005/02/22/real_slams_ms_patent/. Retrieved 6 April 2009.
- ↑ Taft, Darryl K. (21 February 2005). "Real Software Slams Microsofts Patent Effort". eWeek. http://www.eweek.com/article2/0,1759,1766949,00.asp. Retrieved 6 April 2009.
- ↑ Vick, Paul A. Jr.; Barsan, Costica Corneliu; Silver, Amanda K. (14 May 2003). "United States Patent Application: 20040230959". IS NOT OPERATOR. US Patent & Trademark Office. http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220040230959%22.PGNR.&OS=DN/20040230959&RS=DN/20040230959. Retrieved 6 April 2009.
- ↑ Microsoft Brings Programming to the Masses With Visual Studio Express: Company brings the power of code to growing community of hobbyist programmers who seek to integrate technology and software into their everyday lives
- ↑ "What's New in Visual Basic 2010". Microsoft. 2009. http://msdn.microsoft.com/en-us/library/we86c8x2%28VS.100%29.aspx. Retrieved 12 August 2009. "Visual Basic binds to objects from dynamic languages such as IronPython and IronRuby"
- ↑ Migration - Upgrading from Visual Basic 6.0 MSDN – Developer Center – Visual Basic 6.0 Resource Center – Migration –
- ↑ Karl E. Peterson. "Microsoft Basic: 1976-2001,R.I.P.". http://vb.mvps.org. http://vb.mvps.org/vfred/Trust.asp. Retrieved 7 March 2009.
- ↑ Microsoft Basic: 1976-2001, R.I.P
- ↑ Microsoft Basic: 1976-2001, R.I.P
- ↑ Petition to Microsoft
- ↑ Product Family Life-Cycle Guidelines for Visual Basic 6.0
- ↑ Mono Project: VisualBasic.NET support
- ↑ "Module Statement". MSDN - Developer Center. http://msdn.microsoft.com/en-us/library/aaxss7da(VS.80).aspx. Retrieved 20 January 2010.
- ↑ "Main Procedure in Visual Basic". MSDN - Developer Center. http://msdn.microsoft.com/en-us/library/ms235406(VS.80).aspx. Retrieved 20 January 2010.
- ↑ "Visual Basic Version of Hello, World". MSDN - Developer Center. http://msdn.microsoft.com/en-us/library/3cf7t4xt(VS.80).aspx. Retrieved 20 January 2010.
- CLR, and Platform
- Environments and tools
- Microsoft Visual Studio, IDE for .Net languages
- Microsoft Visual Studio Express
- Comparison of programming languages
- Visual Basic for Applications
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