Need Help with Shuffle of a deck

[Dalek Dave]

have you tried applying a number between 1 and 52 to each card, the as each number is picked randomly it is added to an array. on the next random call, it is checked to the contents of the array, and if found to have been picked already is rejected. It will slow doown as the cards are dealt, but then that array will be filled from 1 to 52 in random order, just apply the numbers back to the cards to give a random shuffle.

------------------------------------ "I am always serious about what I do, not necessarily about how I do it." Tom Baker

[Dave Kreskowiak]

You can add your cards to a collection and then pull the cards from random positions out of that collection and add them to another collection.

Private Function GetShuffledDeck() as List(Of Integer)
Dim cards As New List(Of Integer)
For i As Integer = 0 To 51
cards.Add(i)
Next

    Dim RNG As New Random()

    Dim deck As New List(Of Integer)
    While cards.Count > 0
        Dim cardNum As Integer
        cardNum = RNG.Next(0, cards.Count)
        deck.Add(cards(cardNum))
        cards.RemoveAt(cardNum)
    End While

    Return deck

End Function

A guide to posting questions on CodeProject[^]
Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
     2006, 2007, 2008

[riced]

Here's a possible solution. Note that I have not Dimmed all the variables. It's a classic way to do shuffling of card decks.

Private Sub Start_Click()

Dim arrDeck(52)
Randomize

' Fill deck with cards in order 1 to 52
CardCount = 1
Do While CardCount <= 52
arrDeck(CardCount) = Cardcount
CardCount = CardCount + 1
Loop

' Shuufle the deck - end value (100) could be anything, bigger it is the more shuffled deck is
Counter = 0
Do While Counter <= 100
' Get two random card positions
card1 = Int((52 * Rnd) + 1)
card2 = Int((52 * Rnd) + 1)

  ' Swap cards at these positions
  tmpCard        = arrDeck(card1)
  arrDeck(card1) = arrDeck(card2)
  arrDeck(card2) = tmpCard

Loop

' Now output immages in order of deck
CardCount = 1
Do While CardCount <= 52
Subnum = arrDeck(CardCount)
Image1(Subnum).Visible = True
CardCount = CardCount + 1
Loop
End Sub

Regards David R

[riced]

I clicked 'Post Message' when I meant to click 'Preview' :) I was going to add that you should look at how Dave K gets random number sequence. It's really how you should do it as well.

Regards David R

[ymilan]

Thanks for your comments and explanation of your code. It was so easy to understand and made much more sense than what I had. I was trying to do it much more difficult by saying "if one value does not equal the other value, than go ahead and display the images...." I appreciate it. Thanks. Yvonne

[ymilan]

Wow, thanks! This does make total sense, except I have one question which might be a "newbie type:" Cards.Add(i) would produce 0 -51 cards right? Then deck.Add(cards(cardNum" would produce a random ineger and remove at cardnum....since it is in the same function, then there is an end value of 52 right? It seems confusing to me on how the end value is represented in your shuffle procedure. Thanks very much for your time! You are AWESOME!

[ymilan]

Thank you; I will try this...I appreciate your time.

[ymilan]

I went to compile this code in MS VB and it rejected as Compile Error all the values that were not dimmed....any ideas why? Thanks in advance.

[ymilan]

Hmm, seems to compile, but when I click the start button, the program hangs....any ideas?

[riced]

Not without seeing the actual code you did and where it is called. I don't think there's anything in it that should cause a hang. I did not Dim all the variables because I was not sure what you had already declared. Obviously they need to be Dimmed somewhere.

Regards David R

[ymilan]

' I x'd out the lines to show what I am trying to do... Option Explicit Public Sub Main() Start_Game.Show End Sub Private Sub Exit_Click() MsgBox ("Thank you for playing! Good bye") End End Sub Private Sub Start_Click() Dim arrDeck(52) Randomize Dim Cardcount As Integer Dim Counter As Integer Dim Card1 As Integer Dim Card2 As Integer 'Dim CardVal As Integer 'Dim SubNum As Integer ' Fill deck with cards in order 1 to 52 Cardcount = 1 Do While Cardcount <= 52 arrDeck(Cardcount) = Cardcount Cardcount = Cardcount + 1 Loop ' Shuffle the deck - end value (100) Counter = 0 Do While Counter <= 100 ' Get two random card positions Card1 = Int((52 * Rnd) + 1) Card2 = Int((52 * Rnd) + 1) ' Swap cards at these positions Tmpcard = arrDeck(Card1) arrDeck(Card1) = arrDeck(Card2) arrDeck(Card2) = Tmpcard 'CardVal = Tmpcard ? Looking for a single value out of the random cards you made... Loop ' Now output images in order of deck Cardcount = 1 Counter = 0 ' It seems I need a counter in here for Subnum, 0-52 so it can display the cards from 0-52 slots, ' But the array of a single value out of the random cards you made need to be set to another counter, ' Right? I'm not sure...I x'd out the lines to show what I meant... 'Do While Cardcount <= 52 And Counter < 53 'If arrDeck(CardVal) = -1 Then ' arrDeck(CardVal) = Cardcount 'Image1(Cardcount) = CardVal ' Subnum = Counter 'Image1(Subnum).Visible = True Cardcount = Cardcount + 1 'Counter = Counter + 1 ' End If Loop End Sub

[Dave Kreskowiak]

ymilan wrote:

since it is in the same function, then there is an end value of 52 right?

I don't get what your referring to. There is a COUNT of 52 items, 0 to 51 inclusive. The reason I wrote the method this way is because you can eliminate the top part the populates Cards with 0 to 51 and just pass in a collection of cards of any order. This method would then just "shuffle" a randomized deck. For example, you could have a method that passes a deck into this shuffle method a few times, passing in the deck that was returned, to really shuffle the deck. Also, you can create your own Card class and replace the List(Of Integer) references with List(Of Card) instead.

A guide to posting questions on CodeProject[^]
Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
     2006, 2007, 2008

[riced]

I'm not sure why you need all the counters. Your Counter is always one less than Cardcount so is effectively redundant. In Do While Cardcount <= 52 And Counter < 53 both parts of the condition will have same logical value. What is Image1() - it looks like an array but has a Visible property. And this line implies that it is an array of integer: Image1(Cardcount) = CardVal In any case here's a new version of the code that shuffles the images directly. You would need to Dim tmpImage as an appropriate type. To get a single random image after shuffling you could just use Image1(1) i.e. the top of the pack; or you could use tmpImage.

Private Sub Start_Click()
Randomize

'Dim tmpImage As ????
Dim card1 As Integer
Dim card2 As Integer
Dim counter As Integer

' Shuffle the images - end value (100)
Counter = 0
Do While Counter <= 100
' Get two random image positions
card1 = Int((52 * Rnd) + 1)
card2 = Int((52 * Rnd) + 1)

  ' Swap images at these positions
  tmpImage      = Image1(card1)
  Image1(card1) = Image1(card2)
  Image1(card2) = tmpImage

Loop

' Now output images in order
counter = 1
Do While counter <= 52
Image1(counter).Visible = True
counter = counter + 1
Loop
End Sub

What version of VB are you using? I'd assumed VB.NET but I can't see where Image1() would fit in. But, IIRC, in VB6 there is an Image control (not used VB6 for about 5 years). EDIT: forgot to Dim counter :)

Regards David R

[ymilan]

Ok, I get it now. I was thinking along those lines, but got confused. Thanks.

[ymilan]

Ok, sure then, I can just pass the images through directly...then having overkill of counting. I see now. Thanks. As far as the version, perhaps this would be good to ask this question also, I'm using VB6 because that's all I have. It costs for VB.NET right? Not sure. I'm doing a specific game for my Mom, that's why I haven't upgraded am just using an older version. Images() was the visual image of the card I created on the form.

[ymilan]

Ok, I set tmpImage to As Image, is that correct? Then would I have the change the last few lines to reflect Do While Counter <= 52 Image1(TmpImage).Visible = True Counter = Counter + 1 Loop If so, gives an error like object variable or with block variable not set debugs on TmpImage = Image1(Card1)

[riced]

Glad to be of some help - my VB6 is a bit rusty but I should have spotted the use of Image1() :) You'll probably find that Dave K's solution won't work - it's .NET stuff. You can download VB.NET Express editions for free. There's two versions - 2005 and 2008. Probably best to go for 2008. Worth looking into. You can see what's available at http://www.microsoft.com/express/[^]

Regards David R

[riced]

If tmpImage is an Image (it has to be whatever is in Image1() so what type of object does Image1() store?) then you can't use it as an index to Image1(). Using counter as the index will make all the images visible. I don't have VB6 running anymore so I'm relying on memory. :)

Regards David R

[ymilan]

Image1() stores an array... 0-52, was created automatically when I set up the cards on the form.

[riced]

It must be an array of something - the same type as the cards? Can yo see the code that fills the array? That should tell you what the type is. As an alternative, you could try Dimming tmpImage As Variant - that would allow it to hold anything. But you still can't use it as an index into the array.

Regards David R