新建shapefile,自定义字段，新加入记录

            //生成新的shapefile
            IFields pFields = new FieldsClass();
            IFieldsEdit pFieldsEdit = pFields as IFieldsEdit;
            IField pField = new FieldClass();
            IFieldEdit pFieldEdit = pField as IFieldEdit;

            pFieldEdit.Name_2 = "shape";
            pFieldEdit.Type_2 = esriFieldType.esriFieldTypeGeometry;

            IGeometryDef pGeometryDef = new GeometryDefClass();
            IGeometryDefEdit pGeoDefEdit = pGeometryDef as IGeometryDefEdit;
            pGeoDefEdit.GeometryType_2 = esriGeometryType.esriGeometryPolygon;
            pGeoDefEdit.SpatialReference_2 = axMapControl1.SpatialReference;

            pFieldEdit.GeometryDef_2 = pGeometryDef;
            pFieldsEdit.AddField(pField);

            pField = new FieldClass();
            pFieldEdit = pField as IFieldEdit;
            pFieldEdit.Length_2 = 10;
            pFieldEdit.Name_2 = "CODE";
            pFieldEdit.AliasName_2 = "CODE";
            pFieldEdit.Type_2 = esriFieldType.esriFieldTypeString;

            pFieldsEdit.AddField(pField);

            String MapPath = @"E:\data\result";
            String LayerName = "AddFeature";

            
            IWorkspaceFactory pWsf = new ShapefileWorkspaceFactory();
            IFeatureWorkspace pFws=pWsf.OpenFromFile(MapPath,0) as IFeatureWorkspace;
            IFeatureClass pFeatureClass=pFws.CreateFeatureClass(LayerName + ".shp", pFields, null, null, esriFeatureType.esriFTSimple, "shape", "");

新建shapefile,自定义字段，路径自定义。
在文件里加入POLYGON，自定义字段值

            IDataset pDataset = (IDataset)pFeatureClass;
            pFws = (IFeatureWorkspace)pDataset.Workspace;
            IWorkspaceEdit pWorkspaceEdit = (IWorkspaceEdit)pFws;
            pWorkspaceEdit.StartEditing(true);
            pWorkspaceEdit.StartEditOperation();

            IFeatureBuffer pFeatureBuffer = pFeatureClass.CreateFeatureBuffer();
            //Create insert Feature Cursor using buffering = true.
            IFeatureCursor pFeatCursor = pFeatureClass.Insert(true);

            object featureOID;
            //定义新加元素的值
            pFeatureBuffer.set_Value(pFeatureBuffer.Fields.FindField("CODE"),"CODE");

            //生成Polygon**********************************************************
            IPolygon poly = new PolygonClass();
            IPoint pPoint = new PointClass();


            object o = Type.Missing;
            IPointCollection pPc = new MultipointClass();
            pPc = (IPointCollection)poly;

            for (int i = 0; i <= 0; i++ )
            {
                pPoint.PutCoords(200, 400);
                pPc.AddPoint(pPoint, ref o, ref o);

                pPoint.PutCoords(400, 400);
                pPc.AddPoint(pPoint, ref o, ref o);

                pPoint.PutCoords(400, 200);
                pPc.AddPoint(pPoint, ref o, ref o);

                pPoint.PutCoords(200, 200);
                pPc.AddPoint(pPoint, ref o, ref o);
            }

            //生成完毕  ************************************************************

            pFeatureBuffer.Shape = poly;
            featureOID = pFeatCursor.InsertFeature(pFeatureBuffer);

            //Flush the feature cursor to the database       
            //Calling flush allows you to handle any errors at a known time rather then on the cursor destruction.
            pFeatCursor.Flush();

            pWorkspaceEdit.StopEditOperation();
            pWorkspaceEdit.StopEditing(true);

            //释放Cursor
            System.Runtime.InteropServices.Marshal.ReleaseComObject(pFeatCursor);
            axMapControl1.AddShapeFile(MapPath,LayerName+".shp");