# Construct Arc Example (C#)

This example shows how to construct an Arc.

    //--------------------------------------------------------------
    // Preconditions:
    // 1. Create a C# Windows console project.
    // 2. Copy and paste this example into the C# IDE.
    // 3. Add a reference to:
    //    install_dir\APISDK\tlb\DraftSight.Interop.dsAutomation.dll.
    // 4. Add references to System and System.Windows.Forms.
    // 5. Start DraftSight and open a document.
    // 6. Start debugging the project.
    //
    // Postconditions: A message box pops up when an Arc is
    // constructed in the drawing document.
    //----------------------------------------------------------------
    using DraftSight.Interop.dsAutomation;
    using System;
    using System.Runtime.InteropServices;
    using System.Windows.Forms;

    static class Module1
    {
        public static void Main()
        {
            DraftSight.Interop.dsAutomation.Application dsApp;
            Document dsDoc = default(Document);
            Model dsModel = default(Model);
            SketchManager dsSketchManager = default(SketchManager);
            CircleArc dsArc = default(CircleArc);
            double centerX = 0;
            double centerY = 0;
            double centerZ = 0;
            double radius = 0;
            double startAngle = 0;
            double endAngle = 0;

            //Connect to DraftSight
            dsApp = (DraftSight.Interop.dsAutomation.Application)Marshal.GetActiveObject("DraftSight.Application");
    	dsApp.AbortRunningCommand(); // abort any command currently running in DraftSight to avoid nested commands
            //Get active document
            dsDoc = dsApp.GetActiveDocument();
            if (dsDoc != null)
            {
                //Get model space
                dsModel = dsDoc.GetModel();

                //Get Sketch Manager
                dsSketchManager = dsModel.GetSketchManager();

                //Arc parameters (start and end angle values should be in radians)
                centerX = 0.0;
                centerY = 0.0;
                centerZ = 0.0;
                radius = 4.0;
                startAngle = 0.0;
    	    endAngle = Math.PI;

                //Construct an Arc
                dsArc = dsSketchManager.InsertArc(centerX, centerY, centerZ, radius, startAngle, endAngle);

                if (dsArc != null)
                {
                    MessageBox.Show("An Arc was added to drawing.");
                }
            }
            else
            {
                MessageBox.Show("There are no open documents in DraftSight.");
            }
        }
    }