Visual Basic

Dim answers() As String = { "Bleu", "Red", "Black" }

For I As Integer = 0 To answers.Length - 1
 ListBox1.Items.Add((I + 1).ToString() + ". " + answers(I))
Next

Dim I As Integer
Dim answers(2) As String
    
answers(0) = "Bleu"
answers(1) = "Red"
answers(2) = "Black"
    
For I = 0 To UBound(answers)
 List1.AddItem CStr(I + 1) + ". " + answers(I)
Next I

Private data As String() = {"One", "Two", "Three", "Four"}

Public Sub New()
	InitializeComponent()
	addhandler listBox1.format, addressof listBox1_Format
	listBox1.DataSource = data
End Sub

Private Sub listBox1_Format(sender As Object, e As ListControlConvertEventArgs)
	Dim list As IList = DirectCast(DirectCast(sender, ListBox).DataSource, IList)
	Dim idx As Int32 = list.IndexOf(e.ListItem)
        ' format as "1. One",  "2. Two" etc
	e.Value = String.Format("{0}. {1}", idx + 1, e.ListItem)
End Sub

listBox1.Format += New ListControlConvertEventHandler(listBox1_Format)

addhandler listbox1.format, addressof listbox1_format