BuildingCoder.CmdListWalls.Execute C# (CSharp) Method

        public Result Execute(
            ExternalCommandData commandData,
            ref string message,
            ElementSet elements)
        {
            UIApplication app = commandData.Application;
              Document doc = app.ActiveUIDocument.Document;

              FilteredElementCollector walls
            = new FilteredElementCollector( doc );

              walls.OfClass( typeof( Wall ) );

              foreach( Wall wall in walls )
              {
            Parameter param = wall.get_Parameter(
              BuiltInParameter.HOST_AREA_COMPUTED );

            double a = ( ( null != param )
              && ( StorageType.Double == param.StorageType ) )
              ? param.AsDouble()
              : 0.0;

            string s = ( null != param )
              ? param.AsValueString()
              : "null";

            LocationCurve lc = wall.Location as LocationCurve;

            XYZ p = lc.Curve.GetEndPoint( 0 );
            XYZ q = lc.Curve.GetEndPoint( 1 );

            double l = q.DistanceTo( p );

            string format
              = "Wall <{0} {1}> length {2} area {3} ({4})";

            Debug.Print( format,
              wall.Id.IntegerValue.ToString(), wall.Name,
              Util.RealString( l ), Util.RealString( a ),
              s );
              }
              return Result.Succeeded;
        }