ArcGis 計算線段長度

         void CalcLength( string tmpshp)
        {
             var expression =  " float(!SHAPE.LENGTH@YARDS!) ";
            CalculateField cgridX =  new CalculateField(tmpshp,  " Length ", expression);
            cgridX.expression_type =  " PYTHON ";
            IGeoProcessorResult gpResX = gp.Execute(cgridX,  null)  as IGeoProcessorResult;
            Console.WriteLine( " 計算長度 ");
        }

  var gp = new ESRI.ArcGIS.Geoprocessor.Geoprocessor();

            gp.AddOutputsToMap = true;

            gp.OverwriteOutput = true;

            gp.TemporaryMapLayers = true;