Data types, variables, constants and conversions — VB.NET — Visual Basic .NET from Basics to Advanced (with C# Comparison)

2. Data types, variables, constants and conversions

Basic★ Must knowLesson 2 of 12

VB.NET	C#	.NET type	Literal
`Integer`	`int`	`Int32`	`42`, `42I`
`Long`	`long`	`Int64`	`42L`
`Short` / `Byte`	`short` / `byte`	`Int16` / `Byte`	`42S`
`Double` / `Single`	`double` / `float`	`Double` / `Single`	`1.5R` / `1.5F`
`Decimal`	`decimal`	`Decimal`	`1.5D`
`Boolean`	`bool`	`Boolean`	`True` / `False`
`Char`	`char`	`Char`	`"A"c`
`String`	`string`	`String`	`"text"`
`Date`	`DateTime`	`DateTime`	`#10/24/2026#` (M/d/yyyy)
`Object`	`object`	`Object`

Dim count As Integer = 10
Dim price = 99.5D                 ' Decimal, inferred with Option Infer On
Const TaxRate As Decimal = 0.18D
Dim total As Decimal = price * (1 + TaxRate)
Dim nothingYet As String = Nothing     ' Nothing = C# null (or default for value types)
Dim maybe As Integer? = Nothing        ' Nullable(Of Integer)

' Conversions
Dim n1 As Integer = CInt("42")          ' VB conversion keyword (rounds to even for decimals: CInt(2.5) = 2)
Dim n2 As Integer = Integer.Parse("42")
Dim ok As Boolean = Integer.TryParse(input, n1)
Dim d As Double = CDbl(n1)
Dim s As String = n1.ToString()
Dim o As Object = "hello"
Dim str As String = DirectCast(o, String)   ' cast, throws if wrong type (C# (string)o)
Dim str2 As String = TryCast(o, String)     ' returns Nothing if wrong type (C# o as string)
Dim v = CType(o, String)                    ' general conversion

Option Strict On — the most important setting: it forbids implicit narrowing conversions (Dim i As Integer = 3.7 fails) and late binding on Object. With it Off, VB silently converts types and resolves members at runtime — a source of hidden bugs. Turn it on for every project (Project Properties → Compile).