Visual Basic .NET tutorial for beginners

What Visual Basic .NET is and who uses it

VB.NET is the .NET successor of classic Visual Basic (VB6). It compiles to the same intermediate language as C#, so the two languages can share libraries and even be mixed in one solution. It is used mainly for Windows desktop applications (Windows Forms, WPF), internal business tools, ASP.NET web applications and the maintenance of existing VB code bases.

Microsoft continues to support Visual Basic on modern .NET, but it has said that it does not plan to evolve the language with major new features; new .NET features usually appear in C# first. For a new project without existing VB code, C# is the more common choice, but VB.NET remains a readable language for learning programming and for business software.

Install and run Hello, world

Install the .NET SDK (Windows, macOS or Linux). Visual Studio on Windows also includes Visual Basic templates and a visual form designer.

dotnet new console -lang VB -o HelloVB
cd HelloVB
dotnet run
# Hello, world!

' Program.vb
Imports System

Module Program
    Sub Main(args As String())
        Console.WriteLine("Hello, world!")
    End Sub
End Module

A Module holds shared procedures, and Sub Main is the entry point. Comments start with an apostrophe '. Each statement normally ends at the end of the line; there are no semicolons or braces.

Variables and basic types

Declare variables with Dim name As Type. With Option Infer On (the default) you can omit the type when you assign a value. Put Option Strict On at the top of each file (or set it in the project) so that risky implicit conversions become compile errors.

Option Strict On
Module Types
    Sub Main()
        Dim name As String = "Ana"
        Dim age = 30                  ' inferred as Integer
        Console.WriteLine(name & " is " & age.ToString())
        Console.WriteLine($"Next year {name} is {age + 1}")
        Console.WriteLine(7 / 2)      ' 3.5 (always Double)
        Console.WriteLine(7 \ 2)      ' 3 (integer division)
        Console.WriteLine(7 Mod 2)    ' 1
    End Sub
End Module

Control flow

Dim score = 85
If score >= 90 Then
    Console.WriteLine("A")
ElseIf score >= 80 Then
    Console.WriteLine("B")
Else
    Console.WriteLine("C")
End If

Select Case score
    Case 90 To 100
        Console.WriteLine("excellent")
    Case 80 To 89
        Console.WriteLine("good")
    Case Else
        Console.WriteLine("keep going")
End Select

For i = 1 To 3
    Console.WriteLine($"{i} squared is {i * i}")
Next

Dim n = 3
Do While n > 0
    n -= 1
Loop

These statements go inside a Sub. For i = 1 To 3 includes both ends; add Step -1 to count down. For Each item In collection loops over any collection. Use Exit For or Exit Do to leave a loop early. For conditions, prefer AndAlso and OrElse: they stop evaluating as soon as the result is known, while And and Or always evaluate both sides.

Subs, functions and lambdas

A Sub does not return a value; a Function does. Parameters are passed ByVal (a copy) by default; ByRef lets the procedure change the caller's variable. Parameters can be Optional with a default value.

Function Add(a As Integer, b As Integer) As Integer
    Return a + b
End Function

Sub Greet(Optional name As String = "world")
    Console.WriteLine($"Hello, {name}!")
End Sub

Sub Increment(ByRef value As Integer)
    value += 1
End Sub

' Inside Sub Main:
Dim x = 5
Increment(x)                                  ' x is now 6
Greet()                                       ' Hello, world!
Dim square = Function(n As Integer) n * n     ' lambda
Console.WriteLine(square(Add(1, 2)))          ' 9

Arrays, List and Dictionary

Dim nums() As Integer = {3, 1, 2}
Dim five(4) As Integer            ' 5 elements, indexes 0 to 4
Array.Sort(nums)
Console.WriteLine(String.Join(", ", nums))   ' 1, 2, 3

Dim names As New List(Of String) From {"Ana", "Ben"}
names.Add("Cleo")
Console.WriteLine(names.Count)               ' 3

Dim ages As New Dictionary(Of String, Integer)
ages("Ana") = 30
ages("Ben") = 17
For Each pair In ages
    Console.WriteLine($"{pair.Key}: {pair.Value}")
Next

Arrays and lists are indexed from 0 with parentheses: nums(0). Generic types use Of: List(Of String) is the VB form of C#'s List<string>. Note that Dim five(4) declares the upper bound, not the length, so the array has five elements.

Signature features: classes, properties and LINQ queries

VB.NET is fully object-oriented: classes have properties, methods, constructors (Sub New), inheritance (Inherits), interfaces (Implements) and events (Event, RaiseEvent, Handles). LINQ queries can be written in a readable query syntax.

Public Class Person
    Public Property Name As String
    Public Property Age As Integer

    Public Sub New(name As String, age As Integer)
        Me.Name = name
        Me.Age = age
    End Sub
End Class

' Inside Sub Main:
Dim people As New List(Of Person) From {
    New Person("Ana", 30),
    New Person("Ben", 17)
}
Dim adults = From p In people
             Where p.Age >= 18
             Select p.Name
For Each adultName In adults
    Console.WriteLine(adultName)   ' Ana
Next

Because VB is not case-sensitive, Name and name are the same identifier; inside the constructor, Me.Name refers to the property and name to the parameter. Other VB-specific conveniences include With ... End With blocks, XML literals and the My namespace for common tasks.

Error handling

VB.NET uses structured exception handling: Try, Catch, Finally and Throw. A Catch can include a When filter. The older On Error GoTo style from VB6 and VBA still compiles but should not be used in new .NET code.

Function ParseAge(s As String) As Integer
    Dim n As Integer
    If Not Integer.TryParse(s, n) Then
        Throw New FormatException($"Not a number: {s}")
    End If
    If n < 0 Then Throw New ArgumentOutOfRangeException(NameOf(s))
    Return n
End Function

' Inside Sub Main:
Try
    Console.WriteLine(ParseAge("abc"))
Catch ex As FormatException
    Console.WriteLine("Error: " & ex.Message)   ' Error: Not a number: abc
Finally
    Console.WriteLine("done")
End Try

A small complete program: word frequencies

Imports System
Imports System.Collections.Generic
Imports System.Linq

Module WordCount
    Sub Main()
        Dim text = "the cat and the hat and the bat"
        Dim counts As New Dictionary(Of String, Integer)

        For Each word In text.Split(" "c)
            If counts.ContainsKey(word) Then
                counts(word) += 1
            Else
                counts(word) = 1
            End If
        Next

        Dim top = counts.OrderByDescending(Function(kv) kv.Value).Take(2)
        For Each kv In top
            Console.WriteLine($"{kv.Key} {kv.Value}")
        Next
    End Sub
End Module
' the 3
' and 2

VBA: Visual Basic inside Microsoft Office

Visual Basic for Applications (VBA) is the macro language built into Microsoft Office applications such as Excel, Word and Access. It is based on classic Visual Basic, not .NET: it runs inside the Office application, uses the Office object model (workbooks, ranges, documents), and is edited in the VBA editor (Alt+F11 on Windows). The basic syntax of Dim, If, For and Sub is the same, which makes VB.NET knowledge useful for VBA.

' VBA in Excel: write the squares of 1 to 5 into column A
Sub FillSquares()
    Dim i As Long
    For i = 1 To 5
        Cells(i, 1).Value = i * i
    Next i
    MsgBox "Done"
End Sub

Where to go next

• Microsoft Learn: the Visual Basic documentation, including the getting-started guide and the language reference.
• Learn the .NET base class library (collections, files, LINQ); it is shared with C#.
• For desktop apps, try Windows Forms or WPF templates in Visual Studio.
• For Office automation, read the VBA reference on Microsoft Learn for the application you use.