ConvertBase()

Function ConvertBase(Source As Int64, Base As String = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz") As String

  If Source = 0 Then Return "0"

  Dim work As Int64 = Source
  Dim ret As String = ""
  Dim sign As String = ""

  If work < 0 Then
    sign = "-"
    work = Abs(work)
  End If

  Dim i As Integer
  While work <> 0
    i = (work Mod Len(Base))
    ret = Mid(Base, i + 1, 1) + ret
    work = work / Len(Base)
  Wend

  Return sign + ret

End Function