Visual Basic, new to coding. Need to make a list of 100 integers create a shuffled list of 70 results - vb.net

Question

I'm new to coding and I have got firmly stuck on this.
I've created a list in Visual Basic with
Dim integerStable As New List(Of Integer)()
integerStable.Add(0)
integerStable.Add(1)
integerStable.Add(2)
'through to integerStable.Add(99)
I'm trying to keep this list (it can be shuffled as long as all numbers stay in the list in general) and create a 2nd list where it only has 70 results from that shuffle.
I need that list, so I can call on it to perform some tasks for me later.
Can anyone help me work out how to do this? Remember I'm new to coding, but I'll try to follow along.

Answer 1

One of the most efficient ways to create your list would be as follows:
Dim integerStable As New List(Of Integer)
For i = 1 To 100
integerStable.Add(i)
Next
That at least should save you a lot of typing!!
You could also do the following:
Dim integerStable As New List(Of Integer)
Dim i As Integer
While i <= 100
integerStable.Add(i)
i += 1
End While
**Note though that the latter example will give you 101 items as integer is initially set to 0 **
You also need to remember that the list will be 'indexed' from 0 NOT 1 which is an important thing to remember when it comes to manipulating the items with it.

Answer 2

It can be much simpler.
Private Shared PRNG As New Random
' 100 numbers starting at zero, in random order
Private listOnum As List(Of Integer) = Enumerable.Range(0, 100).OrderBy(Function(x) PRNG.Next).ToList
' list of 70 numbers from list of 100
Private list70 As List(Of Integer) = listOnum.Take(70).ToList
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
'did it work?
Dim ct As Integer = 1
For Each n As Integer In list70
Debug.WriteLine("{0}. {1,3}", ct, n)
ct += 1
Next
End Sub
Enumerable.Range takes two arguments. The first is a start number and the second is a count, so in the example it created a list that started at 0 and ended with 99, 100 items. The OrderBy just sorted that list by random numbers.
list70 is created by taking the first 70 items from listOnum.
The Random, PRNG, is created that way so that there is only ONE random that is only initialized once. You can find many problems associated with the incorrect initialization of Random.
edit: Slightly different approach.
Private Shared PRNG As New Random
' 100 numbers starting at zero
Private listOnum As List(Of Integer) = Enumerable.Range(0, 100).ToList
' list of 70 random numbers from list of 100
Private list70 As List(Of Integer) = listOnum.OrderBy(Function(x) PRNG.Next).Take(70).ToList
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
'did it work?
Dim ct As Integer = 1
For Each n As Integer In list70
Debug.WriteLine("{0}. {1,3}", ct, n)
ct += 1
Next
'recreate list of 70
list70 = listOnum.OrderBy(Function(x) PRNG.Next).Take(70).ToList
End Sub