Public _result As Boolean = False
Public _form As PlayCtrlForm = New PlayCtrlForm()
Public Sub IndexOfExample()
   ' reference the play control
   Dim playctrl As PlayCtrl = _form.PlayCtrl

   Try
      ' get the play controls available audio processors
      Dim allProcs As AudioProcessors = playctrl.AudioProcessors

      ' get the play controls selected audio processors
      Dim selProcs As AudioProcessors = playctrl.SelectedAudioProcessors

      ' add a couple processors to the selected audio processors collection
      selProcs.Add(allProcs.Chorus)
      selProcs.Add(allProcs.Echo)

      ' get the indexes of added audio processors
      Dim i As Integer = selProcs.IndexOf(allProcs.Chorus)
      Dim j As Integer = selProcs.IndexOf(allProcs.Echo)

      ' set the result to what we expect
      _result = (i > -1 AndAlso j > -1 AndAlso i <> j)
   Catch e1 As Exception
      _result = False
   End Try
End Sub

public bool _result = false;
public PlayCtrlForm _form = new PlayCtrlForm();
public void IndexOfExample()
{
   // reference the play control
   PlayCtrl playctrl = _form.PlayCtrl;

   try
   {
      // get the play controls available audio processors
      AudioProcessors allProcs = playctrl.AudioProcessors;

      // get the play controls selected audio processors
      AudioProcessors selProcs = playctrl.SelectedAudioProcessors;

      // add a couple processors to the selected audio processors collection
      selProcs.Add(allProcs.Chorus);
      selProcs.Add(allProcs.Echo);

      // get the indexes of added audio processors
      int i = selProcs.IndexOf(allProcs.Chorus);
      int j = selProcs.IndexOf(allProcs.Echo);

      // set the result to what we expect
      _result = (selProcs[i] == selProcs.Chorus && selProcs[j] == selProcs.Echo);
      //_result = (i > -1 && j > -1 && i != j);
   }            
   catch (Exception)
   {
      _result = false;
   }
}