Randomizing an array

Question

I wish to implement the Dr.D.E.Knuth\'s Subtractive RANDOM number generation algorithm. I wish to implement an ATM panel on which when very time user log-in the buttons will be

Answer 1

To set the position of the buttons randomly in the panel, instead of using n from 0 to 9 in the loop, you can use a random value from 0 to 9. Be sure you don't use the same value twice.

Answer 2

You don't need to use a cryptographically secure random number generator for that, nor do you need a separate class.

Private Shared rng As New Random()

Private Shared Function ShuffleArray(Of T)(arr() As T) As T()
    Dim left = Enumerable.Range(0, arr.Length).ToList()
    Dim result(arr.Length - 1) As T

    For i = 0 To arr.Length - 1
        Dim nextIndex = rng.Next(left.Count)
        result(i) = arr(left(nextIndex))
        left.RemoveAt(nextIndex)
    Next

    Return result
End Function

Answer 3

There are quite some "shuffle" algorithms (search Fisher-Yates for example) and they are usually not difficult to implement. The EASIEST (imho) way, ist to use LINQ:

Dim r As New Random
Dim out = (From b In btnArray Order By r.Next Select b).ToArray

Maybe the question is not clear: Do you want to shuffle the POSITIONS of the buttons or do you want to shuffle the CONTENT (buttons) of the Array?