vb.net: List variables not values

Question

what I need does not seem to be too special, but somehow - maybe i am googling the wrong key words - I failed to find anything on the web.

How can I store variables (or references to them?) in Lists / Arrays / or something like that in a way that when I apply a change to the list the change will also be applied to the variable?

Something like:

Dim myList As New List(Of Object)
Dim a As Integer = 5

myList.Add(a)
myList(0) = 10    'here i want a to change as well

If a = 10 Then
    'This is exactly what I want
Else If a = 5 Then
    'This is what i don't want but what I will get
End If

So how can I accomplish this?

Answer 1

An integer is a value type, not a reference type like a class. You have two copies of that value, once in the list and once in the variable. If you want that behavior you needed to store a reference type in the list. For example:

Public Class MyNumber
    Public Sub New(number As int32)
        Value = Number
    End Sub

    Public Property Value As Int32
End Class

Sub Main
    Dim myList As New List(Of MyNumber)
    Dim myFirstNumber As New MyNumber(5)
    myList.Add(myFirstNumber)
    myList(0).Value = 10 

    ' Now both, myFirstNumber.Value and myList(0).Value is 10
End Sub