How does block level scope work with Dim As New in VB.net?

Question

I tried to find this on the web, but my GoogleFu has failed me...

While DataReader.Read
    Dim Foo as New FooBar
    Foo.Property = "Test"
Loop

In VB.net, does this create a new Foo instance every for every loop? Or just one Foo instance with block level scope? Do all blocks (If..EndIf, For..Next) work the same in this regard? I know that Foo is not accessible outside of the block, just not sure if it creates multiple Foo instances.

Answer 1

Since you are in a loop you will get multiple Foo instances. Any foo created inside of a block will not be accessible outside of that block.

Answer 2

This will create a new Foo for every iteration of the loop.

This statement is not 100% true though. In VB.Net it is actually possible to see the previous value of a variable with a bit of tricker. For example

Dim i = 0
While i < 3
  Dim Foo As FooBar
  if Foo IsNot Nothing
    Console.WriteLine(Foo.Property)
  End If
  Foo = New FooBar()
  Foo.Property = "Test" + i  
  i = i + 1
End While 

Answer 3

It creates a new FooBar for each iteration. It is almost the same as this:

Dim Foo as FooBar
While DataReader.Read
    Foo = New FooBar
    Foo.Property = "Test"
Loop

...with the difference being that the FooBar that is created in the last iteration will be available for code below the While loop (within the same block, that is).