Sub PolygonToPolyline()
  Dim pMxDoc As IMxDocument
  Dim pMap As IMap
  Dim pFeatureLayer As IFeatureLayer
  Dim pInFeatureClass As IFeatureClass
  Dim pOutFeatureClass As IFeatureClass
  
  Set pMxDoc = ThisDocument
  Set pMap = pMxDoc.FocusMap
  Set pFeatureLayer = pMxDoc.SelectedLayer
  Set pInFeatureClass = pFeatureLayer.FeatureClass
  '=======================================================================
  Dim ET As New ETGW_Core
  Dim sOutFileName As String
  sOutFileName = "c:\00\polygon_to_polyline.shp"
  Set pOutFeatureClass = ET.PolygonToPolyline(pInFeatureClass, sOutFileName)
  '========================================================================
  Set pFeatureLayer = New FeatureLayer
  Set pFeatureLayer.FeatureClass = pOutFeatureClass
  pFeatureLayer.Name = pOutFeatureClass.AliasName
  pMap.AddLayer pFeatureLayer
End Sub