Creating A Unique Indentifier With A GUID

This page describes how to create a globally unique indentifier.

Creating A GUID

If you need a unique identifier that is certain to be unique across all applications and all computers and all users, you can create a "Globally Unique Indentifier", or GUID. This identifier is universally unqiue. Note that while this value will be unique, there is no meaningful information contained within it. That is, you cannot examine the value of a GUID and discern any information about when or where it was created. The code for creating a GUID is shown below:

Private Declare Function CoCreateGuid Lib "OLE32.DLL" (pGuid As GUID) As Long

Private Type GUID
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(0 To 7) As Byte
End Type

Public Function CreateGUID() As String
    Dim G As GUID
    With G
    If (CoCreateGuid(G) = 0) Then
    CreateGUID = _
        String$(8 - Len(Hex$(.Data1)), "0") & Hex$(.Data1) & _
        String$(4 - Len(Hex$(.Data2)), "0") & Hex$(.Data2) & _
        String$(4 - Len(Hex$(.Data3)), "0") & Hex$(.Data3) & _
        IIf((.Data4(0) < &H10), "0", "") & Hex$(.Data4(0)) & _
        IIf((.Data4(1) < &H10), "0", "") & Hex$(.Data4(1)) & _
        IIf((.Data4(2) < &H10), "0", "") & Hex$(.Data4(2)) & _
        IIf((.Data4(3) < &H10), "0", "") & Hex$(.Data4(3)) & _
        IIf((.Data4(4) < &H10), "0", "") & Hex$(.Data4(4)) & _
        IIf((.Data4(5) < &H10), "0", "") & Hex$(.Data4(5)) & _
        IIf((.Data4(6) < &H10), "0", "") & Hex$(.Data4(6)) & _
        IIf((.Data4(7) < &H10), "0", "") & Hex$(.Data4(7))
    End If
    End With
End Function    

You can then call this function with code like:

Dim UniqueID As String
UniqueID = CreateGUID()

This page last updated: 20-March-2009.