not repeat a random number more then once?

[phamster]

Hello,

I'm having trouble using the Random class. I have this code here:


Dim myRandNum As Random = New Random(DateTime.Now.Millisecond)
Dim i As Integer = 0

i = Integer.Parse(myRandNum.Next(0, 21))

I have this code in a function and everytime I call it it return a random number. The problem is I only want the number to be return/generate once. There be times I call the function and it returns the same number as in the pass. Is there a way to random the number once? I know in C++ you use like "Seed" or something and it will only generate once. Please help, Thanks!

 

[cjard]

Create a list of numbers and remove from it every time you want a random:

Class UniqueRandom

  Private nums as List(Of Integer)
  Private rng as New Random()

  Public Sub New(range as Integer)
    nums = new List(Of Integer)(range)
  
    For i as Integer = 0 to range - 1
      nums.Add(i)
    Next i

  End Sub

  Public Function GetRandomNumber() as Integer
    Dim ret as Integer, idx as Integer
 
    If nums.Count =0 Then Throw New Exception("No more nums available")


    idx = rng.Next(0, nums.Count)
    ret = nums(idx)
    nums.RemoveAt(idx)
    Return ret
  End Function

 

[phamster]

How about sorting an array instead? How would I do that?

 

[cjard]

Array.Sort Method (System)

 

[phamster]

Ok, I try using the sorting array but no luck. Here is exactly what I'm trying to do. I have a card game that holds 21 cards from 1-10 hearts and diamonds only and one joker. Here's my code:

Dim cardArray(20) As Image
Dim myRandNum As Random = New Random(DateTime.Now.Millisecond)

Private Sub main_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
cardArray(0) = Image.FromFile("C:\CardGame\CardGame\Resources\1heart.jpg")
cardArray(1) = Image.FromFile("C:\CardGame\CardGame\Resources\2heart.jpg")
cardArray(2) = Image.FromFile("C:\CardGame\CardGame\Resources\3heart.jpg")
cardArray(3) = Image.FromFile("C:\CardGame\CardGame\Resources\4heart.jpg")
cardArray(4) = Image.FromFile("C:\CardGame\CardGame\Resources\5heart.jpg")
cardArray(5) = Image.FromFile("C:\CardGame\CardGame\Resources\6heart.jpg")
cardArray(6) = Image.FromFile("C:\CardGame\CardGame\Resources\7heart.jpg")
cardArray(7) = Image.FromFile("C:\CardGame\CardGame\Resources\8heart.jpg")
cardArray(8) = Image.FromFile("C:\CardGame\CardGame\Resources\9heart.jpg")
cardArray(9) = Image.FromFile("C:\CardGame\CardGame\Resources\10heart.jpg")
cardArray(10) = Image.FromFile("C:\CardGame\CardGame\Resources\1diamond.jpg")
cardArray(11) = Image.FromFile("C:\CardGame\CardGame\Resources\2diamond.jpg")
cardArray(12) = Image.FromFile("C:\CardGame\CardGame\Resources\3diamond.jpg")
cardArray(13) = Image.FromFile("C:\CardGame\CardGame\Resources\4diamond.jpg")
cardArray(14) = Image.FromFile("C:\CardGame\CardGame\Resources\5diamond.jpg")
cardArray(15) = Image.FromFile("C:\CardGame\CardGame\Resources\6diamond.jpg")
cardArray(16) = Image.FromFile("C:\CardGame\CardGame\Resources\7diamond.jpg")
cardArray(17) = Image.FromFile("C:\CardGame\CardGame\Resources\8diamond.jpg")
cardArray(18) = Image.FromFile("C:\CardGame\CardGame\Resources\9diamond.jpg")
cardArray(19) = Image.FromFile("C:\CardGame\CardGame\Resources\10diamond.jpg")
cardArray(20) = Image.FromFile("C:\CardGame\CardGame\Resources\joker.jpg")
End Sub

Private Sub btnBet_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBet.Click
dealCards()
End Sub

Private Sub dealCards()
picBoxComp1.Image = cardArray(getCard())
picBoxUser1.Image = cardArray(getCard())
picBoxComp2.Image = cardArray(getCard())
picBoxUser2.Image = cardArray(getCard())
picBoxComp3.Image = cardArray(getCard())
picBoxUser3.Image = cardArray(getCard())
End Sub

Function getCard()
Return Integer.Parse(myRandNum.Next(20))
End Function

Is there a better way to randomize the cards?

 

[MattP]

cjard was trying to get you to create a class similar to this one. The class contains a New() Sub that generates your deck. It also contains a GetRandomX function that returns a random 'card' and removes it from the List so you can't select it again.

Friend Class CardDeck
	Private allCardsList As List(Of String)
	Private Shared rand As New Random()

	Public Sub New()
		allCardsList = New List(Of String)(20)

		With allCardsList
			.Add("C:\CardGame\CardGame\Resources\1heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\2heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\3heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\4heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\5heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\6heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\7heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\8heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\9heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\10heart.jpg")
			.Add("C:\CardGame\CardGame\Resources\1diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\2diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\3diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\4diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\5diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\6diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\7diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\8diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\9diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\10diamond.jpg")
			.Add("C:\CardGame\CardGame\Resources\joker.jpg")
		End With
	End Sub

	Public Function GetRandomCard() As String
		Dim idx As Integer
		Dim card As String = Nothing

		If allCardsList.Count <> 0 Then
			idx = rand.Next(0, allCardsList.Count)
			card = allCardsList(idx)
			allCardsList.RemoveAt(idx)
		Else
			Throw New Exception("No cards left in deck")
		End If

		Return card
	End Function

End Clas

Once you've got that set up you can instantiate a new instance of the class and start dealing cards. I would suggest that you store your complete deck as the paths to your images and only load them when you're going to use them.

	Private Sub DealCards()
		Dim deck As New CardDeck

		Me.PicBoxComp1.Image = Image.FromFile(deck.GetRandomCard())
		Me.PicBoxUser1.Image = Image.FromFile(deck.GetRandomCard())
		'...
	End Sub

 

[phamster]

Thank you so much! it works now!