private void updatePointToolStripMenuItem_Click(object sender, EventArgs e) { IMultipoint multipoint; object missing = Type.Missing; IPoint point1 = new PointClass(); point1.PutCoords(10, 10); IPoint point2 = new PointClass(); point2.PutCoords(20, 20); IPointCollection pointCollection = new MultipointClass(); pointCollection.AddPoint(point1, ref missing, ref missing); pointCollection.AddPoint(point2, ref missing, ref missing); point1 = new PointClass(); point1.PutCoords(40, 10); pointCollection.UpdatePoint(1, point1); multipoint = pointCollection as IMultipoint; addFeature("multipoint", multipoint as IGeometry); System.Windows.Forms.MessageBox.Show("X = " + pointCollection.get_Point(1).X + ", Y = " + pointCollection.get_Point(1).Y); this.axMapControl1.Extent = multipoint.Envelope; this.axMapControl1.Refresh(); }