Function Between(value As String, a As String,
b As String) As String
' Get positions for both string arguments.
Dim posA As Integer = value.IndexOf(a)
Dim posB As Integer = value.LastIndexOf(b)
If posA = -1 Then
Return ""
End If
If posB = -1 Then
Return ""
End If

Dim adjustedPosA As Integer = posA + a.Length
If adjustedPosA >= posB Then
Return ""
End If

' Get the substring between the two positions.
Return value.Substring(adjustedPosA, posB - adjustedPosA)
End Function