String() variable in VB

I'm trying to modify a program where there is a variable that stores all the specified file types in a String() variable. What I would like to d开发者_开发问答o is to somehow append to this variable in any way if I want to search another directory or just grab another individual file. Any suggestions would be greatly appreciated.

//Grab files from a directory with the *.txt or *.log as specified in the Combo Box
Dim strFiles As String()
strFiles = System.IO.Directory.GetFiles(txtSource.Text, cmbtype.SelectedItem, IO.SearchOption.AllDirectories)

EDIT: Edited to include code snippet used.

Dim strFiles As String()
Dim listFiles As List(Of String)(strFiles)

If (cmbtype.SelectedItem = "All") Then
    //Do stuff

     For index As Integer = 1 To cmbtype.Items.Count - 1
         Dim strFileTypes As String() = System.IO.Directory.GetFiles(txtSource.Text, cmbtype.Items(index), IO.SearchOption.AllDirectories)
     Next

    //Exit Sub
Else
    listFiles.Add(System.IO.Directory.GetFiles(txtSource.Text, cmbtype.SelectedItem, IO.SearchOption.AllDirectories).ToString())
End If

Right now you're using a String() which is an array of String instances. Arrays are not well suited for dynamically growing structures. A much better type is List(Of String). It is used in very similar manners to a String() but has a handy Add and AddRange method for appending data to the end.

Dim strFiles As New List(Of String)()
strFiles.AddRange(System.IO.Directory.GetFiles(txtSource.Text, cmbtype.SelectedItem, I

O.SearchOption.AllDirectories)

dim listFiles as list(of string)
listFiles = System.IO.Directory.GetFiles(txtSource.Text, cmbtype.SelectedItem, IO.SearchOption.AllDirectories).ToList()
listFiles.Add("..\blah\...\")