The information in this article applies to:
- Microsoft Visual Basic Control Creation, Learning, Professional, and
Enterprise Editions for Windows, version 5.0
- Microsoft Visual Basic Standard, Professional, and Enterprise Editions,
32-bit only, for Windows, version 4.0
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 both Windows 95 and Windows NT.
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
- Add a standard module to a new Visual Basic project. Form1 is created by
default.
- Paste the code below into the code module:
Option Explicit
Type GUID
Data1 As Long
Data2 As Integer
Data3 As Integer
Data4(7) As Byte
End Type
Declare Function CoCreateGuid Lib "OLE32.DLL" (pGuid As GUID) _
As Long
Global Const S_OK = 0 ' return value from CoCreateGuid
Function GetGUID() As String
Dim lResult As Long
Dim lguid As GUID
Dim MyguidString As String
Dim MyGuidString1 As String
Dim MyGuidString2 As String
Dim MyGuidString3 As String
Dim DataLen As Integer
Dim StringLen As Integer
Dim i%
On Error GoTo error_olemsg
lResult = CoCreateGuid(lguid)
If lResult = S_OK Then
MyGuidString1 = Hex$(lguid.Data1)
StringLen = Len(MyGuidString1)
DataLen = Len(lguid.Data1)
MyGuidString1 = LeadingZeros(2 * DataLen, StringLen) _
& MyGuidString1 'First 4 bytes (8 hex digits)
MyGuidString2 = Hex$(lguid.Data2)
StringLen = Len(MyGuidString2)
DataLen = Len(lguid.Data2)
MyGuidString2 = LeadingZeros(2 * DataLen, StringLen) _
& Trim$(MyGuidString2) 'Next 2 bytes (4 hex digits)
MyGuidString3 = Hex$(lguid.Data3)
StringLen = Len(MyGuidString3)
DataLen = Len(lguid.Data3)
MyGuidString3 = LeadingZeros(2 * DataLen, StringLen) _
& Trim$(MyGuidString3) 'Next 2 bytes (4 hex digits)
GetGUID = _
MyGuidString1 & MyGuidString2 & MyGuidString3
For i% = 0 To 7
MyguidString = MyguidString & _
Format$(Hex$(lguid.Data4(i%)), "00")
Next i%
'MyGuidString contains last 8 bytes of Guid (16 hex digits)
GetGUID = GetGUID & MyguidString
Else
GetGUID = "00000000" ' return zeros if function unsuccessful
End If
Exit Function
error_olemsg:
MsgBox "Error " & Str(Err) & ": " & Error$(Err)
GetGUID = "00000000"
Exit Function
End Function
Function LeadingZeros(ExpectedLen As Integer, ActualLen As Integer) _
As String
LeadingZeros = String$(ExpectedLen - ActualLen, "0")
End Function
- Note that calling GetGUID from code will now return a GUID.
Keywords : vb432 VB4WIN vb5all vb5howto
Version : WINDOWS:4.0,5.0
Platform : WINDOWS
Issue type : kbhowto
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