How can I generate GUIDs in Excel?

I know this question is answered, but I think the code in question should look something like what's on this page: http://snipplr.com/view/37940/

Haven't tested, but this code seems to tap into the Windows API to get its GUID's - I would try putting that in a public module and typing =GetGUId() in an Excel cell to see what I'd get. If it works in VB6 you have a great deal of a good chance it works in VBA as well:

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

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

Public Function GetGUID() As String
'(c) 2000 Gus Molina

    Dim udtGUID As GUID

    If (CoCreateGuid(udtGUID) = 0) Then

        GetGUID = _
            String(8 - Len(Hex$(udtGUID.Data1)), "0") & Hex$(udtGUID.Data1) & _
            String(4 - Len(Hex$(udtGUID.Data2)), "0") & Hex$(udtGUID.Data2) & _
            String(4 - Len(Hex$(udtGUID.Data3)), "0") & Hex$(udtGUID.Data3) & _
            IIf((udtGUID.Data4(0) < &H10), "0", "") & Hex$(udtGUID.Data4(0)) & _
            IIf((udtGUID.Data4(1) < &H10), "0", "") & Hex$(udtGUID.Data4(1)) & _
            IIf((udtGUID.Data4(2) < &H10), "0", "") & Hex$(udtGUID.Data4(2)) & _
            IIf((udtGUID.Data4(3) < &H10), "0", "") & Hex$(udtGUID.Data4(3)) & _
            IIf((udtGUID.Data4(4) < &H10), "0", "") & Hex$(udtGUID.Data4(4)) & _
            IIf((udtGUID.Data4(5) < &H10), "0", "") & Hex$(udtGUID.Data4(5)) & _
            IIf((udtGUID.Data4(6) < &H10), "0", "") & Hex$(udtGUID.Data4(6)) & _
            IIf((udtGUID.Data4(7) < &H10), "0", "") & Hex$(udtGUID.Data4(7))
    End If

End Function

Thanks Gus Molina!

If this code works (which I don't doubt), I think you'd get a new set of GUID's whenever the function gets evaluated, which means everytime the sheet gets calculated - when you're saving the workbook, for example. Make sure to copy-pastespecial-values if you need the GUID's for later use... which is somewhat likely.

A VBA approach based on generating random numbers using the Rnd() function, and not on external API calls or Scriptlet.TypeLib:

Public Function CreateGUID() As String
    Do While Len(CreateGUID) < 32
        If Len(CreateGUID) = 16 Then
            '17th character holds version information
            CreateGUID = CreateGUID & Hex$(8 + CInt(Rnd * 3))
        End If
        CreateGUID = CreateGUID & Hex$(CInt(Rnd * 15))
    Loop
    CreateGUID = "{" & Mid(CreateGUID, 1, 8) & "-" & Mid(CreateGUID, 9, 4) & "-" & Mid(CreateGUID, 13, 4) & "-" & Mid(CreateGUID, 17, 4) & "-" & Mid(CreateGUID, 21, 12) & "}"
End Function

This essentially is a VBA implementation of NekojiruSou's answer (it also generates a v4 GUID), and carries the same limitations, but will work in VBA and might be easier to implement.

Note that you can omit the last line to not return the dashes and curly braces in the result.

I used the following function in v.2013 excel vba to create a GUID and is working well..

Public Function GetGUID() As String 
    GetGUID = Mid$(CreateObject("Scriptlet.TypeLib").GUID, 2, 36) 
End Function 

The following Excel expression evaluates to a V4 GUID:

=CONCATENATE(DEC2HEX(RANDBETWEEN(0,4294967295),8),"-",DEC2HEX(RANDBETWEEN(0,65535),4),"-",DEC2HEX(RANDBETWEEN(16384,20479),4),"-",DEC2HEX(RANDBETWEEN(32768,49151),4),"-",DEC2HEX(RANDBETWEEN(0,65535),4),DEC2HEX(RANDBETWEEN(0,4294967295),8))

-or (depending on locale setting/decimal and list separators)-

=CONCATENATE(DEC2HEX(RANDBETWEEN(0;4294967295);8);"-";DEC2HEX(RANDBETWEEN(0;65535);4);"-";DEC2HEX(RANDBETWEEN(16384;20479);4);"-";DEC2HEX(RANDBETWEEN(32768;49151);4);"-";DEC2HEX(RANDBETWEEN(0;65535);4);DEC2HEX(RANDBETWEEN(0;4294967295);8))

Note that the first character of the third group is always 4 to signify a V4 (pseudo-random number generated) GUID/UUID per RFC 4122 section 4.4.

Also note that the first character of the fourth group is always between 8 and B per the same RFC.

Standard disclaimer: the resulting GUIDs/UUIDs are not cryptographically strong.

Edit: remove invisible characters