| Visual Basic | |
|---|---|
 | |
| Paradigm | Multi-paradigm:structured,imperative,object-oriented,declarative,generic,reflective andevent-driven |
| Designed by | Microsoft |
| Developer | Microsoft |
| First appeared | 2001; 24 years ago (2001) |
| Stable release | |
| Typing discipline | Static,both strong and weak,[2]both safe and unsafe,[2]nominative |
| Platform | .NET Framework,Mono,.NET[3][4] |
| OS | ChieflyWindows Also onAndroid,BSD,iOS,Linux,macOS,Solaris, andUnix |
| License | Roslyn compiler:MIT License[5] |
| Filename extensions | .vb |
| Website | docs |
| Majorimplementations | |
| .NET Framework SDK,Roslyn Compiler andMono | |
| Dialects | |
| Microsoft Visual Basic | |
| Influenced by | |
| Classic Visual Basic | |
| Influenced | |
| Small Basic,Mercury | |
Visual Basic (VB), originally calledVisual Basic .NET (VB.NET), is amulti-paradigm,object-orientedprogramming language developed byMicrosoft and implemented on.NET,Mono, and the.NET Framework. Microsoft launched VB.NET in 2002 as the successor to itsoriginal Visual Basic language, the last version of which was Visual Basic 6.0. Although the ".NET" portion of the name was dropped in 2005, this article uses "Visual Basic [.NET]" to refer to all Visual Basic languages released since 2002, in order to distinguish between them and theclassic Visual Basic. Along withC# andF#, it is one of the three main languages targeting the .NET ecosystem. Microsoft updated its VB language strategy on 6 February 2023, stating that VB is a stable language now and Microsoft will keep maintaining it.[6]
Microsoft'sintegrated development environment (IDE) for developing in Visual Basic isVisual Studio. Most Visual Studio editions arecommercial; the only exceptions areVisual Studio Express andVisual Studio Community, which arefreeware. In addition, the.NET Framework SDK includes a freewarecommand-linecompiler called vbc.exe.Mono also includes a command-line VB.NET compiler.
Visual Basic is often used in conjunction with theWindows FormsGUIlibrary to makedesktop apps forWindows. Programming for Windows Forms with Visual Basic involves dragging and dropping controls on a form using aGUI designer and writing corresponding code for each control.
The Windows Forms library is most commonly used to create GUI interfaces in Visual Basic. All visual elements in the Windows Forms class library derive from the Control class. This provides the minimal functionality of a user interface element such as location, size, color, font, text, as well as common events like click and drag/drop. The Control class also has docking support to let a control rearrange its position under its parent.
Forms are typically designed in theVisual StudioIDE. In Visual Studio, forms are created usingdrag-and-drop techniques. A tool is used to place controls (e.g., text boxes, buttons, etc.) on the form (window). Controls haveattributes andevent handlers associated with them. Default values are provided when the control is created, but may be changed by the programmer. Many attribute values can be modified during run time based on user actions or changes in the environment, providing a dynamic application. For example, code can be inserted into the form resize event handler to reposition a control so that it remains centered on the form, expands to fill up the form, etc. By inserting code into the event handler for a keypress in a text box, the program can automatically translate the case of the text being entered, or even prevent certain characters from being inserted.
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Visual Basic usesstatements to specify actions. The most common statement is an expression statement, consisting of anexpression to be evaluated, on a single line. As part of that evaluation,functions or subroutines may becalled andvariables may beassigned new values. To modify the normal sequential execution of statements, Visual Basic provides several control-flow statements identified by reserved keywords.Structured programming is supported by several constructs including two conditional execution constructs (If ...Then ...Else ...End If andSelect Case ...Case ...End Select ) and four iterative execution (loop) constructs (Do ...Loop,For ...To,For Each, andWhile ...End While) . TheFor ...To statement has separate initialisation and testing sections, both of which must be present. (See examples below.) TheFor Each statement steps through each value in a list.
In addition, in Visual Basic:
REM, placed at the beginning of a line or after any number ofspace ortab characters at the beginning of a line, or after other code on a line, indicates that the (remainder of the) line is acomment.The following is a very simple Visual Basic program, a version of the classic "Hello, World!" example created as a console application:
ModuleModule1SubMain()' The classic "Hello, World!" demonstration programConsole.WriteLine("Hello, World!")EndSubEndModule
It prints "Hello, World!" on acommand-line window. Each line serves a specific purpose, as follows:
ModuleModule1
This is a module definition. Modules are a division of code, which can contain any kind of object, like constants or variables, functions or methods, or classes, but can not be instantiated as objects like classes and cannot inherit from other modules. Modules serve as containers of code that can be referenced from other parts of a program.[8]
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 or class.
SubMain()
This line defines a subroutine called "Main". "Main" is the entry point, where the program begins execution.[9]
Console.WriteLine("Hello, world!")
This line performs the actual task of writing the output.Console is a system object, representing a command-line interface (also known as a "console") and granting programmatic access to the operating system'sstandard streams. The program calls theConsole methodWriteLine, which causes the string passed to it to be displayed on the console.
Instead of Console.WriteLine, one could use MsgBox, which prints the message in a dialog box instead of a command-line window.[10]
This piece of code outputsFloyd's Triangle to the console:
ImportsSystem.ConsoleModuleProgramSubMain()DimrowsAsInteger' Input validation.DoUntilInteger.TryParse(ReadLine("Enter a value for how many rows to be displayed: "&vbcrlf),rows)AndAlsorows>=1WriteLine("Allowed range is 1 and {0}",Integer.MaxValue)Loop' Output of Floyd's TriangleDimcurrentAsInteger=1DimrowAsIntegerDimcolumnAsIntegerForrow=1TorowsForcolumn=1TorowWrite("{0,-2} ",current)current+=1NextWriteLine()NextEndSub''' <summary>''' Like Console.ReadLine but takes a prompt string.''' </summary>FunctionReadLine(OptionalpromptAsString=Nothing)AsStringIfpromptIsNotNothingThenWrite(prompt)EndIfReturnConsole.ReadLine()EndFunctionEndModule
Whether Visual Basic .NET should be considered as just another version of Visual Basic or a completely different language is a topic of debate. There are new additions to support new features, such asstructured exception handling and short-circuited expressions. Also, two important data-type changes occurred with the move to VB.NET: compared to Visual Basic 6, theIntegerdata type has been doubled in length from 16 bits to 32 bits, and theLongdata 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 aShort. Similarly, theWindows Forms editor is very similar in style and function to the Visual Basic form editor.
The things thathave changed significantly are the semantics—from those of an object-based programming language running on adeterministic,reference-counted engine based onCOM to a fullyobject-oriented language backed by the.NET Framework, which consists of a combination of theCommon Language Runtime (avirtual machine usinggenerational garbage collection and ajust-in-time compilation engine) and a far largerclass library. The increased breadth of the latter was also a problem that VB developers had to deal with when coming to the language, although this was somewhat addressed by theMy feature in Visual Studio 2005.
The changes altered many underlying assumptions about the "right" thing to do with respect to the performance and maintainability of applications. Some functions and libraries no longer exist; others are available, but not as efficient as the "native" .NET alternatives. Even if they compiled, most converted Visual Basic 6 applications required some level ofrefactoring to take full advantage of the .NET language. Microsoft provided documentation to cover changes in language syntax, debugging applications, deployment, and terminology.[11] A popular trade book designed to ease the transition wasMichael Halvorson'sMicrosoft Visual Basic .NET Professional Step by Step, published in 2002 byMicrosoft Press.
The following simple examples compare VB and VB.NET syntax. They assume that the developer has created a form, placed a button on it and has associated the subroutines demonstrated in each example with the clickevent handler of the mentioned button. Each example creates a "Hello, World" message box after the button on the form is clicked.
Visual Basic 6:
PrivateSubCommand1_Click()MsgBox"Hello, World"EndSub
VB.NET (MsgBox or MessageBox class can be used):
PrivateSubButton1_Click(senderAsobject,eAsEventArgs)HandlesButton1.ClickMsgBox("Hello, World")EndSub
Sub andEnd Sub statements when the corresponding button is double-clicked in design view. Visual Basic .NET will also generate the necessaryClass andEnd Class statements. The developer need only add the statement to display the "Hello, World" message box.Call).Command1 andButton1 are not obligatory. However, these are default names for a command button in Visual Basic 6 and VB.NET respectively.Handles keyword is used to make the subButton1_Click a handler for theClick event of the objectButton1. In Visual Basic 6, event handler subs must have a specific name consisting of the object's name (Command1), an underscore (_), and the event's name (Click, henceCommand1_Click).MessageBox.Show in theMicrosoft.VisualBasic namespace which can be used (instead ofMsgBox) similarly to the corresponding function in Visual Basic 6. There is a controversy[12] about which function to use as a best practice (not only restricted to showing message boxes but also regarding other features of theMicrosoft.VisualBasic namespace). 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, usingint (C#) orInteger (VB.NET) instead ofSystem.Int32).ByValsenderasObject,ByValeasEventArgs has become optional.The following example demonstrates a difference between Visual Basic 6 and VB.NET. Both examples close theactive window.
Visual Basic 6:
SubcmdClose_Click()UnloadMeEndSub
VB.NET:
SubbtnClose_Click(senderAsObject,eAsEventArgs)HandlesbtnClose.ClickClose()EndSub
The 'cmd' prefix is replaced by the 'btn' prefix, conforming to the new convention previously mentioned.[which?]
Visual Basic 6 did not provide common operator shortcuts. The following are equivalent:
Visual Basic 6:
SubTimer1_Timer()'Reduces Form Height by one pixel per tickMe.Height=Me.Height-1EndSub
VB.NET:
SubTimer1_Tick(senderAsObject,eAsEventArgs)HandlesTimer1.TickMe.Height-=1EndSub
C# and Visual Basic are Microsoft's first languages made to program on the .NET Framework (later addingF# and more; others have also added languages). Though C# and Visual Basic are syntactically different, that is where the differences mostly end. Microsoft developed both of these languages to be part of the same .NET Framework development platform. They are both developed, managed, and supported by the same language development team at Microsoft.[13] They compile to the same intermediate language (IL), which runs against the same .NET Framework runtime libraries.[14] Although there are some differences in the programming constructs, their differences are primarily syntactic and, assuming one avoids the Visual Basic "Compatibility" libraries provided by Microsoft to aid conversion from Visual Basic 6, almost every feature in VB has an equivalent feature in C# and vice versa. Lastly, both languages reference the same Base Classes of the .NET Framework to extend their functionality. As a result, with few exceptions, a program written in either language can be run through a simple syntax converter to translate to the other. There are many open source and commercially available products for this task.
Requires a button called Button1.
PublicClassForm1PrivateSubButton1_Click(senderAsObject,eAsEventArgs)HandlesButton1.ClickMsgBox("Hello world!",MsgBoxStyle.Information,"Hello world!")' Show a message that says "Hello world!".EndSubEndClass
ModuleModule1SubMain()Console.WriteLine("Hello world!")' Write in the console "Hello world!" and start a new line.Console.ReadKey()' The user must press any key before the application ends.EndSubEndModule
Requires a TextBox titled 'TextBox1' and a button called Button1.
PublicClassForm1PrivateSubButton1_Click(senderAsObject,eAsEventArgs)HandlesButton1.ClickCreateObject("Sapi.Spvoice").Speak(TextBox1.Text)EndSubEndClass
ModuleModule1PrivateVoice=CreateObject("Sapi.Spvoice")PrivateTextAsStringSubMain()Console.Write("Enter the text to speak: ")' Say "Enter the text to speak: "Text=Console.ReadLine()' The user must enter the text to speak.Voice.Speak(Text)' Speak the text the user has entered.EndSubEndModule
Succeedingthe classic Visual Basic version 6.0, the first version of Visual Basic .NET debuted in 2002. As of 2020[update], ten versions of Visual Basic .NET are released.
The first version, Visual Basic .NET, relies on.NET Framework 1.0. The most important feature ismanaged code, which contrasts with the classic Visual Basic.
Visual Basic .NET 2003 was released with.NET Framework 1.1. New features included support for the.NET Compact Framework and a better VB upgradewizard. Improvements were also made to the performance and reliability of .NET IDE (particularly thebackground compiler) and runtime. In addition, Visual Basic .NET 2003 was available in the Visual Studio.NET Academic Edition, distributed to a certain number of scholars[weasel words] from each country without cost.
After Visual Basic .NET 2003, Microsoft dropped ".NET" from the name of the product, calling the next version Visual Basic 2005.
For this release, Microsoft added many features intended to reinforce Visual Basic .NET's focus as arapid application development platform and further differentiate it fromC#., including:
My.Form2.Text=" MainForm " rather thanSystem.WindowsApplication1.Forms.Form2.text=" MainForm "To bridge the gaps between itself and other .NET languages, this version added:
Visual Basic 2005 introduced theIsNot operator that makes'If X IsNot Y' equivalent to'If Not X Is Y'. It gained notoriety[20] when it was found to be the subject of a Microsoft patent application.[21][22]
Visual Basic 9.0 was released along with.NET Framework 3.5 on November 19, 2007.
For this release, Microsoft added many features, including:
In April 2010, Microsoft released Visual Basic 2010. Microsoft had planned to useDynamic Language Runtime (DLR) for that release[23] but shifted to a co-evolution strategy between Visual Basic and sister language C# to bring both languages into closer parity with one another. Visual Basic's innate ability to interact dynamically with CLR and COM objects has been enhanced to work with dynamic languages built on the DLR such asIronPython andIronRuby.[24] The Visual Basic compiler was improved to infer line continuation in a set of common contexts, in many cases removing the need for the " _" line continuation characters. Also, existing support of inline Functions was complemented with support for inline Subs as well as multi-line versions of both Sub and Function lambdas.[25]
Visual Basic 2012 was released alongside.NET Framework 4.5. Major features introduced in this version include:[further explanation needed]
Visual Basic 2013 was released alongside .NET Framework 4.5.1 with Visual Studio 2013. Can also build .NET Framework 4.5.2 applications by installing Developer Pack.[26]
Visual Basic 2015 (code named VB "14.0") was released with Visual Studio 2015. Language features include a new "?." operator to perform inline null checks, and a new string interpolation feature is included to format strings inline.[27]
Visual Basic 2017 (code named VB "15.0") was released with Visual Studio 2017.Extends support for new Visual Basic 15 language features with revision 2017, 15.3, 15.5, 15.8. Introduces new refactorings that allow organizing source code with one action.[28][29]
Visual Basic 2019 (code named VB "16.0") was released with Visual Studio 2019.[30] It is the first version of Visual Basic focused on .NET Core.[31]
A minor update was later released as Visual Basic 16.9 which only added the ability to consume init-only properties.[32] This was done to maintain compatibility with C# 9.0[33] per the current development strategy of the language.[34]
Visual Basic received no updates with the release of Visual Studio 2022.[34]
The official Visual Basic compiler is written in Visual Basic and is available on GitHub as a part of the.NET Compiler Platform.[35] The creation of open-source tools for Visual Basic development has been slow compared toC#, although theMono development platform provides an implementation of Visual Basic-specific libraries and a Visual Basic 2005 compatiblecompiler written in Visual Basic,[36] as well as standard framework libraries such asWindows Forms GUI library.
MonoDevelop was anopen-source alternativeIDE. TheGambas environment is also similar but distinct from Visual Basic, as is the Visual FB Editor forFreeBasic.
{{cite web}}:Missing or empty|title= (help)With the new DLR, we have support for IronPython, IronRuby, Javascript, and the new dynamic VBx compile
Visual Basic binds to objects from dynamic languages such as IronPython and IronRuby
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