asp.net read and write txt file method __.net

        String strfile= "Asp.txt";
        
        String strout=string. Empty;
        if (! File.exists (System.Web.HttpContext.Current.Server.MapPath (strfile)))
        {
        }
        else
        {
            using ( StreamReader sr = new StreamReader (System.Web.HttpContext.Current.Server.MapPath (strfile), System.Text.Encoding.Default))
            {
              strout= Sr. ReadToEnd ();
          }

        Response.Write ("SSSs");

=============================== "TXT document is relatively small, the content is very few when a kind of writing"
        using System.test;
        String txt = file.readalltext ("D:\\aaa.sys", Encoding.default);
        Response.Write ("" "+ txt +" "");

System.IO.File.WriteAllText ("E:\\asp_1.txt", "I Love You!wang na");  Be sure to have absolute path

String txtpath = Server.MapPath ("~\\public\\attinfo\\") + "Test.txt"; 
StreamWriter sw = new StreamWriter (Txtpath, False, System.Text.Encoding.Default); 
Sw. WriteLine ("Hello World"); 
Sw. WriteLine (""); Output empty line 
SW. WriteLine ("ASP. NET network programming. "); 
Sw. Close ();