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A GUID is a string (or 128bit number), normally used as an ID that is guaranteed to be unique on all machines (assuming they have a network card). They are used as IDs for COM interfaces and classes, database keys and unique IDs for network machines and users.
There are several ways of creating GUIDs but the most common way is to use the CoCreateGuid() function. You can then convert this to a string using the StringFromGUID2() function.
Private Type GUID Data1 As Long Data2 As Integer Data3 As Integer Data4(0 To 7) As Byte End Type Private Declare Function CoCreateGuid Lib "OLE32.DLL" (pGUID As GUID) As Long Private Declare Function StringFromGUID2 Lib "OLE32.DLL" (pGUID As GUID, _ ByVal lpString As Long, ByVal MaxLength As Long) As Long Public Function CreateGUID() As String Dim GUID As GUID Dim GUIDString As String 'Create the GUID If CoCreateGuid(GUID) Then GUIDString = "" Else 'Pre allocate a string to hold the GUID GUIDString = String$(38, 0) 'Convert to a string StringFromGUID2 GUID, StrPtr(GUIDString), 39 End If CreateGUID = GUIDString End Function