Android Question implementing random none reapeated integers

Addo · Jan 17, 2019

i am trying to generate a random none repeated integers

i do something like following

B4X:

Sub randnumbers(Upperange As Int) As Int
    
Dim d As Int
d = Rnd(0, Upperange)
Do While d < 1002
d = Rnd(0, Upperange)
Loop

Return d   
    
End Sub

is there a better approach to do a randomize integers ?

DonManfred · Jan 17, 2019

1. I dont see how you are preventring generating two identical integers!?
2.

PassionDEV said:
Do While d < 1002

If you dont want values <1002 then you should directly use

B4X:

Dim d As Int
d = Rnd(1002, Upperange)

Erel · Jan 17, 2019

The question is not clear enough.

B4X:

Dim s As B4XSet = B4XCollections.CreateSet
For i = 1 To 100
   s.Add(Rnd(1, 1000))
Next
For Each number As Int In s.AsList
   Log(number)
Next

Note that the set size might be smaller than 100.

LucaMs · Jan 17, 2019

Erel said:
The question is not clear enough.

B4X:

Dim s As B4XSet = B4XCollections.CreateSet For i = 1 To 100 s.Add(Rnd(1, 1000)) Next For Each number As Int In s.AsList Log(number) Next

Note that the set size might be smaller than 100.

Creates your code a list of non-repeated numbers?

I was already writing the following code:

B4X:

    Private lstNumbers As List
   lstNumbers.Initialize
   Dim UpperRange As Int = 1000
   Dim RandomNumber As Int = Rnd(1, UpperRange + 1)
   For i = 0 To 9
       Do Until lstNumbers.IndexOf(RandomNumber) = -1
           RandomNumber = Rnd(1, UpperRange + 1)
       Loop
       lstNumbers.Add(RandomNumber)
   Next
   lstNumbers.Sort(True)
   Log(lstNumbers) 'ignore

LucaMs · Jan 17, 2019

LucaMs said:
Creates your code a list of non-repeated numbers?

Erel said:
B4XSet - A set is a collection of unique items

Erel · Jan 17, 2019

I gave you a hint: Note that the set size might be smaller than 100

LucaMs · Jan 17, 2019

Erel, your code creates a list of non-repeated numbers but not the number of elements you want.

Try your code so:

Erel said:
For i = 1 To 500
s.Add(Rnd(1, 1000))
Next
Log(s.AsList.Size)

Erel · Jan 17, 2019

This is why I wrote:

1. The question is not clear enough.
2. Note that the set size might be smaller than 100.

LucaMs · Jan 17, 2019

Erel said:
2. Note that the set size might be smaller than 100.

Yes but even if you chose to create a list of only 2 elements, you might get just one element (if you are unlucky )

Android Question implementing random none reapeated integers

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