For more information on the ON_BrepCylinder function, see it's definition in opennurbs_brep.h.

C++

  CRhinoCommand::result CCommandTest::RunCommand(
          const CRhinoCommandContext& context 
          )
  {
    ON_3dPoint center_point( 0.0, 0.0, 0.0 );
    double radius = 5.0;
    ON_3dPoint height_point( 0.0, 0.0, 10.0 );
    ON_3dVector zaxis = height_point - center_point;
    ON_Plane plane( center_point, zaxis );
    ON_Circle circle( plane, radius );
    ON_Cylinder cylinder( circle, zaxis.Length() );
    ON_Brep* brep = ON_BrepCylinder( cylinder, TRUE, TRUE );
    if( brep )
    {
      CRhinoBrepObject* cylinder_object = new CRhinoBrepObject();
      cylinder_object->SetBrep( brep );
      if( context.m_doc.AddObject(cylinder_object) )
        context.m_doc.Redraw();
      else
        delete cylinder_object;
    }


    return CRhinoCommand::success;
  }

VB.NET (Rhino 4)

  Public Overrides Function RunCommand(ByVal context As IRhinoCommandContext) _
    As IRhinoCommand.result


    Dim center_point As New On3dPoint(0, 0, 0)
    Dim radius As Double = 5
    Dim height_point As New On3dPoint(0, 0, 10)
    Dim zaxis As On3dVector = height_point - center_point
    Dim plane As New OnPlane(center_point, zaxis)
    Dim circle As New OnCircle(plane, radius)
    Dim cylinder As New OnCylinder(circle, zaxis.Length())
    Dim brep As OnBrep = OnUtil.ON_BrepCylinder(cylinder, True, True)
    If (Not (brep Is Nothing)) Then
      Dim cylinder_object As New MRhinoBrepObject()
      cylinder_object.SetBrep(brep)
      If (context.m_doc.AddObject(cylinder_object)) Then
        context.m_doc.Redraw()
      End If
    End If


    Return IRhinoCommand.result.success
  End Function

C# (Rhino 4)

  public override IRhinoCommand.result RunCommand(IRhinoCommandContext context)
  {
    On3dPoint center_point = new On3dPoint(0, 0, 0);
    double radius = 5;
    On3dPoint height_point = new On3dPoint(0, 0, 10);
    On3dVector zaxis = height_point - center_point;
    OnPlane plane = new OnPlane(center_point, zaxis);
    OnCircle circle = new OnCircle(plane, radius);
    OnCylinder cylinder = new OnCylinder(circle, zaxis.Length());


    OnBrep brep = OnUtil.ON_BrepCylinder(cylinder, true, true);
    if( brep != null )
    {
      MRhinoBrepObject cylinder_object = new MRhinoBrepObject();
      cylinder_object.SetBrep(brep);
      if (context.m_doc.AddObject(cylinder_object))
        context.m_doc.Redraw();
    }
    return IRhinoCommand.result.success;
  }