Non repeating positive random numbers, over a given range - vb6

Question

am generating a game using vb 6.0, at one face i need to generate non repeating random numbers between 1 and 100. am using the following code for generating the random numbers
dim n(10) as integer
for i=0 to 9
n(i)=round(rnd*100)
next i
the code is within a for loop hence it generate 10 Nos. randomly, but it includes repeating numbers and also '0', is their any suggestion to avoid repeating numbers and '0'
then output of my code is:
n()={42,14,10,22,5,42,12,0,59,72}
the numbers 42 is appear two times in the array and 0 cannot be avoided
thanks in advance

Answer 1

Here is a simple technique
Dim n(10) As Integer
Dim choice(100) As Integer
' Create a list of possible numbers
For i = 0 To 100
choice(i) = i
Next
' Populate the array with unique numbers
For i = 1 To 10
lastix = 101 - i
' Find one that has not been selected
ix = Round(Rnd * lastix)
' Assign it
n(i) = choice(ix)
' Replace with one that has not been used
choice(ix) = choice(lastix)
Next
You can use the same technique for shuffling cards.

Answer 2

To avoid 0, multiply by 99 and add 1. To avoid duplicates, keep track of what you generated and retry if you get a duplicate. (Since you need only a few numbers. If you need many, shuffle an array of all possible outcomes and take the initial members.)

Answer 3

the solution below is not the fastest, but makes up by that for being easy ...
it uses a hidden listbox control which contains the required values and retreives a random one every time
the values in this example are just the squared numbers of the index
run the project and click the command button to see what happens. it should show messageboxes with the square numbers in random order
'1 form with:
'1 listbox control : name=List1
'1 command button : name=Command1
Option Explicit
Private Sub Command1_Click()
Dim intIndex As Integer
'generate a new random sequence every time
Randomize Timer
'loop through the list and retreive 1 random value at a time
With List1
Do While .ListCount > 0
intIndex = Int(Rnd * .ListCount)
MsgBox .List(intIndex)
'remove the used item from the list
.RemoveItem intIndex
Loop
End With 'List1
End Sub
Private Sub Form_Load()
Dim intIndex As Integer
'hide listbox
List1.Visible = False
'fill listbox with values (squares)
List1.Clear
For intIndex = 1 To 10
List1.AddItem CStr(intIndex * intIndex)
Next intIndex
End Sub
btw i am just using 10 numbers so you dont have to click through 100 messageboxes :)