Gath Adams

Random numbers can be a pain if you have to generate new sequences each day. The normal ‘randomize()’ statement is seeded from the system timer so if you are running the generator at the same time, then there is a chance you will get the same sequence.

Over at  Random.org, Mads Haahr has been generating random numbers using atmospheric noise since 1998, and his method has the pseudo-random number generators build into VB.Net beat.

Here is the VB.Net wrapper to call random.org and get your numbers:

Imports System.Net

Public Class clsRandom
    Public Sub RandomizeReseed()
        Dim iSeed(0) As Integer

        iSeed = RandomIntegers(-1000000000, 1000000000, 1)
        Randomize(iSeed(0))
    End Sub

    Public Function RandomIntegers(ByVal MinValue As Integer, _
        ByVal MaxValue As Integer, _
        ByVal NumberCount As Integer) As Integer()

        Dim iC As Integer
        Dim iRetInts As Integer()
        Dim sRetIntsAsStr As String()
        Dim sURL As String

        If Math.Abs(MinValue) > 1000000000 Then
            Dim ex As New Exception("MinValue cannot be greater than 1,000,000,000 or less than -1,000,000,000")
            Throw ex
        End If

        If Math.Abs(MaxValue) > 1000000000 Then
            Dim ex As New Exception("MaxValue cannot be greater than 1,000,000,000 or less than -1,000,000,000")
            Throw ex
        End If

        If MinValue > MaxValue Then
            Dim ex As New Exception("MinValue cannot be greater than MaxValue")
            Throw ex
        End If

        If NumberCount > 10000 Then
            Dim ex As New Exception("NumberCount cannot be greater than 10,000")
            Throw ex
        End If

        sURL = "http://www.random.org/integers/?"
        sURL = sURL & "num=" & NumberCount
        sURL = sURL & "&min=" & MinValue
        sURL = sURL & "&max=" & MaxValue
        sURL = sURL & "&col=1&base=10&format=plain&rnd=new"

        sRetIntsAsStr = CallRandomDotOrg(sURL)
        ReDim iRetInts(sRetIntsAsStr.GetUpperBound(0))
        For iC = 0 To sRetIntsAsStr.GetUpperBound(0)
            iRetInts(iC) = sRetIntsAsStr(iC)
        Next

        RandomIntegers = iRetInts
    End Function

    Private Function CallRandomDotOrg(ByVal sGetURL As String) As String()
        Dim objWebClient As New WebClient()

        Dim sResponse As String
        Dim sReturnInts() As String

        sResponse = objWebClient.DownloadString(sGetURL)
        If Right$(sResponse, 1) = vbLf Then
            sResponse = Left$(sResponse, Len(sResponse) - 1)
        End If

        sReturnInts = sResponse.Split(vbLf)

        CallRandomDotOrg = sReturnInts
    End Function
End Class

Using the class is pretty simple. You can get an array of integers using the function:
RandomIntegers(MinValue, MaxValue, Count)

or you can seed the built-in random number generator with a truly random number by calling
RandomizeReseed()

This post brought to you by WeGotDomain.com - Over 10,000 Aged domains for sale!

Related posts:

1. Getting Flights info from the Kayak API in ASP.Net

Name (required)

Mail (will not be published) (required)

Website