How To Use CoCreateGUID API to Generate a GUID with VB

As a programmer, you may need to generate GUIDs (Globally Unique Identifiers) for various purposes. This article describes how to generate a GUID in Visual Basic using the CoCreateGuid API.

NOTE: The code in this article is not intended and cannot be used to create or change a GUID automatically generated by Visual Basic for custom ActiveX components. GUIDs automatically generated by Visual Basic cannot be altered.

The code below can be used to create a GUID in Visual Basic. The code calls the CoCreateGuid API found in OLE32.DLL on Windows 95, Windows 98, Windows Me, Windows NT and Windows 2000. In order to call the API correctly, a variable of type GUID must be passed. This code creates a custom type, named GUID, with four parts that represent the individual parts separated by dashes that you would see when viewing a CLSID or GUID in the system registry. This code simply returns a GUID; however, it can be modified to add the dashes if desired:

Step By Step Example

1. Add a standard module to a new Visual Basic project. Form1 is created by default.
2. Paste the code below into the code module:

   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
   					

3. Add a Command Button to the form, and add the following code to the form:

         Private Sub Command1_Click()
              MsgBox GetGuid
         End Sub
   					

4. Press F5 to run the project, and click the Command Button.

RESULT: A GUID is generated and shown within a MessageBox.