Visual Basic Cheat Sheet

Module Program
    Sub Main()
        Console.WriteLine("Hello, World!")
    End Sub
End Module

' Single line comment

REM Alternative comment

' TODO: Multi-line comments use continuation
' with apostrophes on each line

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

Dim name As String = "John"
Dim age As Integer = 30
Dim price As Decimal = 19.99D
Dim isActive As Boolean = True

Dim x = 10          ' Integer
Dim s = "Hello"     ' String
Dim d = 3.14        ' Double

Const PI As Double = 3.14159
Const MAX_SIZE As Integer = 100

Integer, Long, Short, Byte
Double, Single, Decimal
Boolean, Char, String
Date, DateTime, Object

Dim age As Integer? = Nothing
Dim name As String = Nothing

If age.HasValue Then
    Console.WriteLine(age.Value)
End If

Dim sum = a + b
Dim diff = a - b
Dim prod = a * b
Dim quot = a / b      ' Real division
Dim intQuot = a \ b   ' Integer division
Dim remainder = a Mod b
Dim power = a ^ b

a = b    ' Equal
a <> b   ' Not equal
a > b    ' Greater
a < b    ' Less
a >= b   ' Greater or equal
a <= b   ' Less or equal

If a > 0 And b > 0 Then
If a > 0 Or b > 0 Then
If Not flag Then
If a > 0 AndAlso b > 0 Then  ' Short-circuit
If a > 0 OrElse b > 0 Then   ' Short-circuit

Dim full = first & " " & last  ' Concatenation
Dim full2 = first + " " + last
Dim repeat = "x" * 5  ' Not available, use New String("x"c, 5)

If age >= 18 Then
    Console.WriteLine("Adult")
Else
    Console.WriteLine("Minor")
End If

If score >= 90 Then
    grade = "A"
ElseIf score >= 80 Then
    grade = "B"
Else
    grade = "F"
End If

Select Case dayOfWeek
    Case 1
        Console.WriteLine("Monday")
    Case 2 To 5
        Console.WriteLine("Weekday")
    Case 6, 7
        Console.WriteLine("Weekend")
    Case Else
        Console.WriteLine("Invalid")
End Select

Dim result = If(condition, valueIfTrue, valueIfFalse)
Dim msg = If(age >= 18, "Adult", "Minor")

For i As Integer = 1 To 10
    Console.WriteLine(i)
Next

For i As Integer = 10 To 1 Step -1
    Console.WriteLine(i)
Next

Dim fruits() As String = {"Apple", "Banana", "Orange"}
For Each fruit In fruits
    Console.WriteLine(fruit)
Next

While count < 10
    Console.WriteLine(count)
    count += 1
End While

Do While count < 10
    Console.WriteLine(count)
    count += 1
Loop

Do Until count >= 10
    Console.WriteLine(count)
    count += 1
Loop

For i = 1 To 100
    If i = 50 Then Exit For
    If i Mod 2 = 0 Then Continue For
    Console.WriteLine(i)
Next

Sub Greet(name As String)
    Console.WriteLine("Hello, " & name)
End Sub

' Call
Greet("Alice")

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

' Call
Dim sum = Add(5, 3)

Function Power(base As Integer, Optional exp As Integer = 2) As Integer
    Return CInt(Math.Pow(base, exp))
End Function

Dim x = Power(5)      ' 25
Dim y = Power(2, 3)   ' 8

Sub Swap(ByRef a As Integer, ByRef b As Integer)
    Dim temp = a
    a = b
    b = temp
End Sub

Dim square = Function(x) x * x
Dim result = square(5)  ' 25

Dim numbers(4) As Integer  ' 5 elements (0-4)
Dim names() As String = {"Alice", "Bob", "Charlie"}

numbers(0) = 10
Console.WriteLine(numbers(0))

Dim length = numbers.Length
Array.Sort(numbers)
Array.Reverse(numbers)

Dim list As New List(Of Integer)
list.Add(10)
list.Add(20)
list.Remove(10)
Console.WriteLine(list.Count)

Dim dict As New Dictionary(Of String, Integer)
dict.Add("Alice", 25)
dict("Bob") = 30
Console.WriteLine(dict("Alice"))

Dim numbers() = {1, 2, 3, 4, 5}
Dim evens = numbers.Where(Function(n) n Mod 2 = 0).ToArray()
Dim doubled = numbers.Select(Function(n) n * 2).ToList()

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

Dim person As New Person("John", 30)
Console.WriteLine(person.Name)

Public Class Employee
    Inherits Person

    Public Property Salary As Decimal
End Class

Interface IDrawable
    Sub Draw()
End Interface

Class Circle
    Implements IDrawable

    Public Sub Draw() Implements IDrawable.Draw
        Console.WriteLine("Drawing circle")
    End Sub
End Class