如下图，读取每行文本，每行文本再按空格分开读取一个字符串，输出到另一个文本：

CAD环境下，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
    {
        [CommandMethod("xx")]
        public void Demo()
        {
            string filename = @"E:\vba\888.txt";
            string filename1 = @"E:\vba\999.txt";
            try
            {
                File.Delete(filename1); 
            string[] contents = File.ReadAllLines(filename);
            List<List<string>> list = new List<List<string>>();
            for (int i = 0; i < contents.Length; i++)
            {
                string[] cont = contents[i].Split(new char[] { ' ' });
                List<string> sublist = new List<string>();
                for (int j = 0; j < cont.Length; j++)
                {
                    sublist.Add(cont[j]);
                    File.AppendAllLines(filename1, cont);

                }
                list.Add(sublist);
            }

            }
            catch (System.Exception)
            {

                throw;
            }
         
        }  
    }
}