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Q176790: HOWTO: Use CoCreateGUID API to Generate a GUID with VB

Article: Q176790
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.0,5.0,6.0
Operating System(s): 
Keyword(s): kbnokeyword kbActiveX kbVBp kbVBp400 kbVBp500 kbVBp600 kbOSWin95 kbOSWin98 kbGrpDSVB kb
Last Modified: 27-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Control Creation Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SUMMARY
=======

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.

MORE INFORMATION
================

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.

Additional query words:

======================================================================
Keywords          : kbnokeyword kbActiveX kbVBp kbVBp400 kbVBp500 kbVBp600 kbOSWin95 kbOSWin98 kbGrpDSVB kbDSupport kbOSWinME 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbVB400Search kbVB400 kbZNotKeyword3
Version           : :4.0,5.0,6.0
Issue type        : kbhowto

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