C#操作txt文件,进行清空添加操作的小例子

//把txt清空
           FileStreamstream=File.Open(Adr,FileMode.OpenOrCreate,FileAccess.Write);
           stream.Seek(0,SeekOrigin.Begin);
           stream.SetLength(0);
           stream.Close();
           //向txt里面追加信息
           StreamWritersw=newStreamWriter(Adr,true,Encoding.GetEncoding("gb2312"));
           sw.WriteLine(str);
           sw.Flush();
           sw.Close();