Q:

How to convert a List(of Long) into a string array? (VB)

I want to convert a List (of Long) into a string array.
Reason: it's a list of database IDs and I want to make a comma delimited string to pass into a stored proc.
I tried this:
Dim commaDelimitedList As String = String.Join(",", itemIDList.Cast(Of String)().ToArray)

but I'm clearly not using the Cast correctly since it throws an exception:
System.InvalidCastException: Unable to cast object of type 'System.Int64' to type 'System.String'..
Is there a way to get Cast working for this, or am I stuck with ConvertAll and a delegate function?

A:

If you can use LINQ this will do what you want:
Dim commaDelimitedList  As String = String.Join(",", itemIDList.Select(Function(itemID) itemID.ToString()).ToArray())

A:

Can't cast - unless you can LINQ, you have to convert each int into a string so you have an array of strings 
   CLR 2.0 has a ConvertAll() method that will do that... 
string s =  String.Join(",",
              l1.ConvertAll<string>(delegate(int i) 
                 { return i.ToString(); }).ToArray()); 

