Guid Structure (System)

Imports System.Runtime.InteropServices

' Guid for the interface IMyInterface.
<Guid("F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4")> _
Interface IMyInterface
   Sub MyMethod()
End Interface

' Guid for the coclass MyTestClass.
<Guid("936DA01F-9ABD-4d9d-80C7-02AF85C822A8")> _
Public Class Example
   Implements IMyInterface

   Public Sub MyMethod() Implements IMyInterface.MyMethod
   End Sub

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim IMyInterfaceAttribute As Attribute = Attribute.GetCustomAttribute(GetType(IMyInterface), GetType(GuidAttribute))

      ' The Value property of GuidAttribute returns a string. 
      outputBlock.Text += String.Format("IMyInterface Attribute: " + CType(IMyInterfaceAttribute, GuidAttribute).Value) & vbCrLf

      ' Using the string to create a guid.
      Dim myGuid1 As New Guid(CType(IMyInterfaceAttribute, GuidAttribute).Value)
      ' Using a byte array to create a guid.
      Dim myGuid2 As New Guid(myGuid1.ToByteArray())

      ' Equals is overridden and so value comparison is done though references are different.
      If myGuid1.Equals(myGuid2) Then
         outputBlock.Text &= "myGuid1 equals myGuid2" & vbCrLf
      Else
         outputBlock.Text &= "myGuid1 not equals myGuid2" & vbCrLf
      End If
      ' Equality operator can also be used to determine if two guids have same value.
      If myGuid1.ToString() = myGuid2.ToString() Then
         outputBlock.Text &= "myGuid1 == myGuid2" & vbCrLf
      Else
         outputBlock.Text &= "myGuid1 != myGuid2" & vbCrLf
      End If
   End Sub
End Class
' The example displays the following output:
'       IMyInterface Attribute: F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4
'       myGuid1 equals myGuid2
'       myGuid1 == myGuid2

using System;
using System.Runtime.InteropServices;

// Guid for the interface IMyInterface.
[Guid("F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4")]
interface IMyInterface
{
   void MyMethod();
}

// Guid for MyTestClass.
[Guid("936DA01F-9ABD-4d9d-80C7-02AF85C822A8")]
public class Example : IMyInterface
{
   public void MyMethod() { }

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Attribute IMyInterfaceAttribute = Attribute.GetCustomAttribute(typeof(IMyInterface), typeof(GuidAttribute));

      // The Value property of GuidAttribute returns a string. 
      outputBlock.Text += "IMyInterface Attribute: " + ((GuidAttribute)IMyInterfaceAttribute).Value + "\n";

      // Using the string to create a guid.
      Guid myGuid1 = new Guid(((GuidAttribute)IMyInterfaceAttribute).Value);
      // Using a byte array to create a guid.
      Guid myGuid2 = new Guid(myGuid1.ToByteArray());

      // Equals is overridden and so value comparison is done though references are different.
      if (myGuid1.Equals(myGuid2))
         outputBlock.Text += "myGuid1 equals myGuid2" + "\n";
      else
         outputBlock.Text += "myGuid1 not equals myGuid2" + "\n";

      // Equality operator can also be used to determine if two guids have same value.
      if (myGuid1 == myGuid2)
         outputBlock.Text += "myGuid1 == myGuid2" + "\n";
      else
         outputBlock.Text += "myGuid1 != myGuid2" + "\n";
   }
}
// The example displays the following output:
//       IMyInterface Attribute: F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4
//       myGuid1 equals myGuid2
//       myGuid1 == myGuid2