Select the Midpoint of an Edge Example (C#)

//-------------------------------------------------------
// Preconditions:
// 1. Open a part document.
// 2. Select an edge.
// 3. Open the Immediate window.
//
// Postconditions:
// 1. Puts a midpoint on the selected edge.
// 2. Place the cursor on the selected edge to see the
//    midpoint.
// 3. Examine the Immediate window.
//------------------------------------------------------
using SolidWorks.Interop.sldworks;
using SolidWorks.Interop.swconst;
using System.Runtime.InteropServices;
using System;
using System.Diagnostics;

namespace PlaceMidPointOnEdge_CSharp.csproj
{
    partial class SolidWorksMacro
    {

        const long swSelEDGES = 1;
        const long swSelREFERENCECURVES = 26;
        const long swSelPOINTREFS = 41;
        const long swSelREFEDGES = 51;

        public void Main()
        {
            ModelDoc2 swModel = default(ModelDoc2);
            PartDoc swPart = default(PartDoc);
            SelectionMgr swSelMgr = default(SelectionMgr);
            long nSelType = 0;

            swModel = (ModelDoc2)swApp.ActiveDoc;
            swPart = (PartDoc)swModel;
            swSelMgr = (SelectionMgr)swModel.SelectionManager;

            nSelType = swSelMgr.GetSelectedObjectType3(1, -1);
            Debug.Print("SelType (before) = " + nSelType);

            swModel.SelectMidpoint();

            nSelType = swSelMgr.GetSelectedObjectType3(1, -1);
            Debug.Print("SelType (after ) = " + nSelType);

        }


        public SldWorks swApp;

    }

}