如图所示原始坐标格式，xy按空格分开，将坐标按顺序在cad中画成多段线：

 坐标xy分开并按行重新输入txt，效果如下：

代码如下 ：

using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Runtime;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using AcTools;
using Autodesk.AutoCAD.Geometry;
using System.IO;namespace Acdemo
{public class Acdemo{private void Addl(Entity ent ) {Database db = HostApplicationServices.WorkingDatabase;using (Transaction tr = db.TransactionManager .StartTransaction ()){BlockTable bt = (BlockTable)tr.GetObject (db.BlockTableId ,OpenMode .ForRead  );BlockTableRecord btr = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord .ModelSpace ],OpenMode.ForWrite );btr.AppendEntity (ent);tr.AddNewlyCreatedDBObject(ent,true );tr.Commit ();   }}[CommandMethod("xx")]public void Demo(){Database db = HostApplicationServices.WorkingDatabase;string filename = @"E:\d\8.txt";string filename1 = @"E:\d\999.txt";try{File.Delete(filename1); string contents = File.ReadAllText(filename);List<List<string>> list = new List<List<string>>();Polyline pl = new Polyline();  pl.Closed = true;   pl.ColorIndex = 3;string[] cont = contents.Split(new char[] { ' ', '\n' });double x, y;File.AppendAllLines(filename1, cont);for (int i = 0; i < cont.Length / 2; i++){   x = Convert.ToDouble (cont[2*i]);y = Convert.ToDouble(cont[2*i+1]);pl.AddVertexAt(i, new Point2d(x, y),0.0,0.0,0.0);}Addl (pl);}catch (System.Exception){throw;}}  }
}

其中有个封装函数addl，为封装事务写入实体到数据库的函。

若输入坐标格式有误，则用以下程序，可在命令行提示错误信息：

using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Runtime;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using AcTools;
using Autodesk.AutoCAD.Geometry;
using System.IO;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.ApplicationServices;namespace Acdemo
{public class Acdemo{private void Addl(Entity ent ) {Database db = HostApplicationServices.WorkingDatabase;using (Transaction tr = db.TransactionManager .StartTransaction ()){BlockTable bt = (BlockTable)tr.GetObject (db.BlockTableId ,OpenMode .ForRead  );BlockTableRecord btr = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord .ModelSpace ],OpenMode.ForWrite );btr.AppendEntity (ent);tr.AddNewlyCreatedDBObject(ent,true );tr.Commit ();   }}[CommandMethod("xx")]public void Demo(){Database db = HostApplicationServices.WorkingDatabase;string filename = @"E:\d\8.txt";string filename1 = @"E:\d\999.txt";try{File.Delete(filename1); string contents = File.ReadAllText(filename);List<List<string>> list = new List<List<string>>();Polyline pl = new Polyline();  pl.Closed = true;   pl.ColorIndex = 3;string[] cont = contents.Split(new char[] { ' ', '\n' });double x, y;File.AppendAllLines(filename1, cont);for (int i = 0; i < cont.Length / 2; i++){   //x = Convert.ToDouble (cont[2*i]);//y = Convert.ToDouble(cont[2*i+1]);bool bx = double.TryParse(cont[2*i], out x);bool by = double.TryParse (cont[2*i + 1],out y);if (bx==false ||  by == false ) {Editor ed = Application .DocumentManager.MdiActiveDocument .Editor ;ed.WriteMessage($"有错误,{cont[2 * i]},{cont[2 * i+1]}");}pl.AddVertexAt(i, new Point2d(x, y),0.0,0.0,0.0);}Addl (pl);}catch (System.Exception){throw;}}  }
}