References in VB.NET

Question

Somewhat unclear to me are references (pointers?) to classes in VB.NET. The question I am about to ask can be answered by a little bit of testing, but I was wondering if any

Answer 1

When passing classes byval/byref in VB.NET it is possible to think of it in terms of C programming and pointers such that -

ByVal = passing arguments via - a pointer 
ByRef = passing arguments via - a pointer to a pointer

Take strings as an example

' ByRef - modify str pointer to "point" to a new string
Sub Test_Ref(ByRef str as string)
    str = "New String ByRef"
End Sub

' ByVal - can't modify str pointer must return a (pointer to) new string
Function Test_Val(ByVal str as String) as String
    Return "New String ByVal"
End Sub

Sub Main()
    Dim strTest as String = "Hello World!"
    Console.WriteLine(strTest)
    Test_Ref(strTest)
    Console.WriteLine(strTest)
    Test_Val(strTest)
    Console.WriteLine(strTest) ' oops still pointing to same string
    strTest = Test_Val(strTest)
    Console.WriteLine(strTest) ' that's better :)
End Sub