Visual Basic Cheat Sheet

Variables & Types

Dim name As String = "Ada": Declare a variable with a type
Dim count = 0: Type inferred (Option Infer On)
Const TaxRate As Decimal = 0.2D: Constant
Integer / Long / Double / Decimal / Boolean / Char / String / Date: Everyday types
CInt("42") / CDbl(x) / CStr(n) / CType(obj, T): Conversion functions
Integer.TryParse(text, n): Safe parsing (returns True/False)
Option Strict On: File header: forbid implicit narrowing conversions

"Hello, " & name: Concatenation (use &, not +)
$"Total: {total:F2}": Interpolated string with a format
s.Length / s.ToUpper() / s.Trim(): Common members
s.Substring(0, 3) / s.Replace("a", "b"): Substring (zero-based) / replace
s.Split(","c) / String.Join(", ", items): Split / join ("c"c is a Char literal)
"She said ""hi""": Escape a quote by doubling it

If x > 0 Then ... ElseIf x < 0 Then ... Else ... End If: Conditional
Select Case n : Case 1 To 5 : ... : Case Is > 5 : ... : End Select: Multi-way branch with ranges
For i = 1 To 10 Step 2 ... Next: Counting loop (inclusive)
For Each item In items ... Next: Loop over a collection
Do While cond ... Loop / Do ... Loop Until cond: Condition loops
Exit For / Continue For: Leave a loop / skip to the next iteration

Sub Greet(name As String) ... End Sub: Procedure with no return value
Function Square(x As Integer) As Integer : Return x * x : End Function: Function with a return value
ByRef total As Integer: Parameter the procedure can change
Optional greeting As String = "Hello": Optional parameter with a default
ParamArray values() As Integer: Any number of arguments
Function(x) x * 2: Lambda expression

Public Class Person ... End Class: Class declaration
Public Property Name As String: Auto-implemented property
Public Sub New(name As String): Constructor
Inherits Animal / Overrides / Overridable / MustOverride: Inheritance keywords
Implements IComparable(Of Person): Implement an interface
Shared Function Create() As Person: Shared (static) member
Me / MyBase: Current instance / base class

Dim nums() As Integer = {1, 2, 3}: Array literal; nums(0) is the first item
New List(Of String) From {"a", "b"}: Generic list with initializer
New Dictionary(Of String, Integer): Key/value dictionary
From n In nums Where n > 1 Select n * 10: LINQ query syntax
nums.Where(Function(n) n > 1).Sum(): LINQ method syntax

Try ... Catch ex As IOException ... Finally ... End Try: Exception handling
Throw New ArgumentException("bad value"): Raise an exception
Using reader As New StreamReader(path) ... End Using: Dispose a resource automatically
File.ReadAllLines(path) / File.WriteAllText(path, text): Quick file access (System.IO)
Async Function LoadAsync() As Task(Of String): Asynchronous function
Dim text = Await client.GetStringAsync(url): Wait for a task without blocking