VERSION 4.00
Begin VB.Form Form1 
   Caption         =   "Sieve Test"
   ClientHeight    =   2820
   ClientLeft      =   3792
   ClientTop       =   2688
   ClientWidth     =   4728
   Height          =   3204
   Left            =   3744
   LinkTopic       =   "Form1"
   ScaleHeight     =   2820
   ScaleWidth      =   4728
   Top             =   2352
   Width           =   4824
   Begin VB.TextBox Text1 
      Height          =   492
      Left            =   2280
      TabIndex        =   0
      Top             =   1200
      Width           =   972
   End
   Begin VB.CommandButton Command1 
      Caption         =   "Start sieving"
      Height          =   492
      Left            =   2280
      TabIndex        =   1
      Top             =   2280
      Width           =   972
   End
   Begin VB.Label Label1 
      Caption         =   "Enter the ending number"
      Height          =   492
      Left            =   840
      TabIndex        =   2
      Top             =   1200
      Width           =   1092
   End
End
Attribute VB_Name = "Form1"
Attribute VB_Creatable = False
Attribute VB_Exposed = False
Private Sub Command1_Click()
Dim testArray As New BitArray
Dim Size As Long, Foo As Variant
Foo = Text1.Text
If Not IsNumeric(Foo) Then
 MsgBox ("Enter a number please")
 Text1.Text = ""
 Text1.SetFocus
 Exit Sub
End If

Size = Val(Text1.Text)
theTime = Timer
testArray.BitSet = Size
Dim I As Long, Count As Long, K As Long
For I = 1 To Size
 testArray.turnOnBit = I
Next I
I = 2
  Do While I * I <= Size
    If testArray.getBit(I) Then
     K = 2 * I
     Do While K <= Size
       testArray.turnOffBit = K
       K = I + K
     Loop
    End If
    I = I + 1
  Loop
For I = 2 To Size
    If testArray.getBit(I) Then Count = Count + 1
Next I
Cls
Print "There are"; Count; " primes up to"; Size; "."
Print "Total time taken was "; Timer - theTime; " seconds."
Set testArray = Nothing
End Sub