Visual Basic (.NET)

Simple example

The following is a very simple Visual Basic program, a version of the classic "Hello, World!" example created as a console application:

Module Module1

    Sub Main()
        ' The classic "Hello, World!" demonstration program
        Console.WriteLine("Hello, World!")
    End Sub

End Module

It prints "Hello, World!" on a command-line window. Each line serves a specific purpose, as follows:

Module Module1

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.

Sub Main()

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's standard streams. The program calls the Console method WriteLine, which causes the string passed to it to be displayed on the console.

Instead of Console.WriteLine, an alternative is MsgBox, which prints the message in a dialog box instead of a command-line window.^[10]

Complex example

This piece of code outputs Floyd's Triangle to the console:

Imports System.Console

Module Program

    Sub Main()
        Dim rows As Integer

        ' Input validation.
        Do Until Integer.TryParse(ReadLine("Enter a value for how many rows to be displayed: " & vbcrlf), rows) AndAlso rows >= 1
            WriteLine("Allowed range is 1 and {0}", Integer.MaxValue)
        Loop
      
        ' Output of Floyd's Triangle
        Dim current As Integer = 1
        Dim row As Integer 
        Dim column As Integer
        For row = 1 To rows
            For column = 1 To row
                Write("{0,-2} ", current)
                current += 1
            Next

            WriteLine()
        Next
    End Sub

    ''' <summary>
    ''' Like Console.ReadLine but takes a prompt string.
    ''' </summary>
    Function ReadLine(Optional prompt As String = Nothing) As String
        If prompt IsNot Nothing Then
            Write(prompt)
        End If

        Return Console.ReadLine()
    End Function

End Module

Comparison with the classic Visual Basic

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 as structured exception handling and short-circuited expressions. Also, two important data-type changes occurred with the move to VB.NET: compared to Visual Basic 6, 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 editor is very similar in style and function to the Visual Basic form editor.

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 was also a problem that VB developers had to deal with when coming to the language, although this was somewhat addressed by the My 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 of refactoring 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 was Michael Halvorson's Microsoft Visual Basic .NET Professional Step by Step, published in 2002 by Microsoft Press.

Private Sub Command1_Click()
    MsgBox "Hello, World"
End Sub

Private Sub Button1_Click(sender As object, e As EventArgs) Handles Button1.Click
    MsgBox("Hello, World")
End Sub

Sub cmdClose_Click()
    Unload Me
End Sub

Sub btnClose_Click(sender As Object, e As EventArgs) Handles btnClose.Click
    Close()
End Sub

Sub Timer1_Timer()
    'Reduces Form Height by one pixel per tick
    Me.Height = Me.Height - 1
End Sub

Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    Me.Height -= 1
End Sub

Comparison with C#

C# and Visual Basic are Microsoft's first languages made to program on the .NET Framework (later adding F# 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) known as CIL, 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. Both languages reference the same Base Classes of the .NET Framework to extend their functionality, and both languages can reference compiled code written in the other language. 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.

Hello World!

Windows Forms Application

Requires a button called Button1.

Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        MsgBox("Hello world!", MsgBoxStyle.Information, "Hello world!") ' Show a message that says "Hello world!".
    End Sub
End Class

Module Module1

    Sub Main()
        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.
    End Sub
End Module

Speaking

Public Class Form1
    
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        CreateObject("Sapi.Spvoice").Speak(TextBox1.Text)
    End Sub
End Class

Module Module1
    Private Voice = CreateObject("Sapi.Spvoice")
    Private Text As String

    Sub Main()
        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.
    End Sub
End Module

2002 (VB 7.0)

The first version, Visual Basic .NET, relies on .NET Framework 1.0. The most important feature is managed code, which contrasts with the classic Visual Basic.

2003 (VB 7.1)

Visual Basic .NET 2003 was released with .NET Framework 1.1. 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 .NET IDE (particularly the background 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 from each country without cost.

2005 (VB 8.0)

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 a rapid application development platform and further differentiate it from C#., including:

• Edit and Continue feature^{[further explanation needed]}
• Design-time expression evaluation^{[further explanation needed]}
• A pseudo-namespace called "My", which provides:^[15][16]
  • Easy access to certain areas of the .NET Framework that otherwise require significant code to access like using My.Form2.Text = " MainForm " rather than System.WindowsApplication1.Forms.Form2.text = " MainForm "
  • Dynamically generated classes (e.g. My.Forms)
• Improved VB-to-VB.NET converter^[17]
• A "using" keyword, simplifying the use of objects that require the Dispose pattern to free resources
• Just My Code feature, which hides (steps over) boilerplate code written by the Visual Studio .NET IDE and system library code during debugging
• Data Source binding, easing database client/server development

To bridge the gaps between itself and other .NET languages, this version added:

• Generics^[18]
• Partial classes, a method of defining some parts of a class in one file and then adding more definitions later; particularly useful for integrating user code with auto-generated code
• Operator overloading and nullable types^[19]
• Support for unsigned integer data types commonly used in other languages

Visual Basic 2005 introduced the IsNot 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]

2008 (VB 9.0)

Visual Basic 9.0 was released along with .NET Framework 3.5 on November 19, 2007.

For this release, Microsoft added many features, including:

• A true conditional operator, "If(condition as Boolean, truepart, falsepart)", to replace the "IIf" function.
• Anonymous types
• Support for LINQ
• Lambda expressions
• XML Literals
• Type Inference
• Extension methods

2010 (VB 10.0)

In April 2010, Microsoft released Visual Basic 2010. Microsoft had planned to use Dynamic 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 as IronPython and IronRuby.^[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]

2012 (VB 11.0)

Visual Basic 2012 was released alongside .NET Framework 4.5. Major features introduced in this version include:^{[further explanation needed]}

• Asynchronous programming with "async" and "await" statements
• Iterators
• Call hierarchy
• Caller information
• "Global" keyword in "namespace" statements

2013 (VB 12.0)

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]

2015 (VB 14.0)

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]

2017 (VB 15.x)

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]

2019 (VB 16.x)

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]

2022 (VB 17.0)

Visual Basic 17.0 enables the System.Runtime.CompilerServices.CallerArgumentExpressionAttribute.

2026 (VB 17.13)

Visual Basic 17.13 recognizes the unmanaged generic constraint and the System.Runtime.CompilerServices.OverloadResolutionPriorityAttribute for method resolution.