how to shuffle array in VB? - vb.net

Question

I'm trying to create and application which will shuffle an string array and produce 2 totally different versions where no element will match each other
like for example the initial array is A, B, C, D, E than the shuffled array must be B, D, E, A, C.
In my case when I suffle them and try to produce an output I get shuffled array but they are completely identical to each other. It seems like the values in last array override the values of the previous ones.
I tried to protect them but I don't know how to do it. Please can anybody give me a hint about what am I doing wrong?
Dim myArray() As String = {"A", "B", "C", "D", "E"}
This is the code of the button which triggers shuffle
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
RendomOutput1(myArray)
End Sub
End Class
THis is the function that shuffles first array:
Sub RendomOutput1(ByVal x() As String)
Dim t As Integer
Dim Temp As String
For i As Integer = 0 To x.Count - 1
Dim rnd As New Random
t = rnd.Next(0, x.Count - 1)
Temp = x(t)
x(t) = x(i)
x(i) = Temp
Next
RandomOutput2(x)
End Sub
This is the function which produces another array and prints the result:
Sub RendomOutput2(ByRef y() As String)
Dim y1() As String = y' May be I shall lock or somehow protect y1 here?
'Lock(y1) doesn't work
Dim t As Integer
Dim Temp As String
For i As Integer = 0 To y.Count - 1
Dim rnd As New Random
t = rnd.Next(0, y.Count - 1)
Temp = y(t)
y(t) = y(i)
y(i) = Temp
Next
For i As Integer = 0 To x.Count - 1
Label1.Text &= y1(i) & " IS NOT " & y(i) & vbCrLf
Next
End Sub
IN the result arrays y1 and y are different from initial but identical to each other. Does anybody know how can I make them different. Probably lock y1 array or something. Thank you in advance

Answer 1

This line
Dim y1() As String = y
doesn't create a new array - it creates a reference to an existing array. So you'll have two array references (y and y1) but only one array (both references point to the same array). When you make changes to y those changes are visible through y1 because both of them refer to the same underlying array.
What you need is 2 distinct array instances where the data held be the arrays are duplicated (that is, you need 2 array references that point to 2 different arrays). Then changes made to one array will not affect the other array.
For example:
' Create new array from the input array
Dim y1() As String = new String(y.Count-1){}
For i As Integer = 0 To y.Count-1
y1(i) = y(i)
Next i
Alternatively, you can just clone the array:
Dim y1() As String = y.Clone()
Behind the scenes this results in the same thing.

Answer 2

Here's a simple routine for shuffling any array:
Public Sub Shuffle(Of T)(ByRef A() As T)
Dim last As Integer = A.Length - 1
Dim B(last) As T
Dim done(last) As Byte
Dim r As New Random(My.Computer.Clock.TickCount)
Dim n As Integer
For i As Integer = 0 To last
Do
n = r.Next(last + 1)
Loop Until Not done(n)
done(n) = 1
B(i) = A(n)
Next
A = B
End Sub
Note that some elements could remain at their original index by chance.