copy files in c# asp.net

        const int BUFFSIZE = 1024;
        Stream instream = File.OpenRead(Server.MapPath("images/login_icon.png"));
        Stream outstream = File.OpenWrite(Server.MapPath("images/israr.png"));
            byte[] buffer = new Byte[BUFFSIZE];
            int numbytes;
            while ((numbytes=instream.Read(buffer,0,BUFFSIZE)) > 0)
            {
               outstream.Write(buffer,0,numbytes);
            }
            instream.Close();
            outstream.Close();