Shuffle an Array

[cpradio]

I have an array that I want to shuffle. By shuffle I mean move the elements around to different locations.

Does anyone know of a simple way to make this happen? I did a search on "random array" and a search on "shuffle array" but neither turned up the results I had hoped for.

-Matt

[Edneeis]

Its probably easier to retrieve them randomly then to move them around inside the array to a random order.

[cpradio]

cant it has to be programmed in.

[Pirate]

Did you have a look at Reverse() Function in the array obj ? I don't know if that's what want .

[cpradio]

Doesn't reverse just reverse the order?? that isnt shuffling the order.

[hellswraith]

Do something like this (psudocode):

For i=0 to array.length

' get a random number between 0 and array.length
Dim Random as ......a random number code.

Dim Temp as String

Temp = array(i)

array(i) = array(Random)

array(Random) = Temp

Next

So basically, you go through each item, and randomly switch it with another item.

[Evad]

I just threw this together... Let me know how it works...

place code inside a button

Dim items() As String = {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"}
ShuffleArray(items)

Module

  Public Function ShuffleArray(ByRef Obj())
    Dim xCount As Integer = 0
    Dim TmpArray()
    ReDim TmpArray(0)
    Dim xVal As Integer

    Randomize()
    Do Until xCount = Obj.Length
      xVal = CInt(Int(Obj.Length * Rnd()))
      If Not Obj(xVal) Is Nothing Then
        If xCount > 0 Then ReDim Preserve TmpArray(xCount)
        TmpArray(xCount) = Obj(xVal)
        xCount += 1
        Array.Clear(Obj, xVal, 1)
      End If
    Loop

    Dim i As Integer = 0
    For i = 0 To xCount - 1
      Obj(i) = TmpArray(i)
    Next

  End Function

[hellswraith]

There is no need for all that. I took my psudocode and wrote it out for you.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim items() As String = {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"}
        items = ShuffleArray(items)
    End Sub
 
    Private Function ShuffleArray(ByVal obj() As Object) As Object()
        Dim Temp As Object
        Dim randomNum As Integer
        Dim i As Integer
        For i = 0 To obj.Length - 1
            randomNum = New System.Random().Next(1, obj.Length - 1)
            Temp = obj(i)
            obj(i) = obj(randomNum)
            obj(randomNum) = Temp
        Next
        ShuffleArray = obj
    End Function