namespace file {     class MyFile     {         string FilePath;         byte[] byData = http://www.mamicode.com/new byte[100]; public char[] MyData = new char[1000]; public string reslutstr = null; public MyFile() { } public MyFile(string path) { FilePath = path; } public void ReadFile1() { try { FileStream file = new FileStream(FilePath, FileMode.Open); file.Seek(0, SeekOrigin.Begin); file.Read(byData, 0, 100); //byData传进来的字节数组,用以接受FileStream对象中的数据,第2个参数是字节数组中开始写入数据的位置,它通常是0,表示从数组的开端文件中向数组写数据,最后一个参数规定从文件读多少字符. Decoder d = Encoding.Default.GetDecoder(); d.GetChars(byData, 0, byData.Length, MyData, 0); //Console.WriteLine(MyData); foreach (char ch in MyData) { reslutstr += ch.ToString(); } file.Close(); } catch (IOException e) { Console.WriteLine(e.ToString()); } } public void ReadFile2( ) { StreamReader sr = new StreamReader(FilePath, Encoding.Default); String line; while ((line = sr.ReadLine()) != null) { reslutstr += line; // Console.WriteLine(line.ToString()); } } public void SaveFile1(string savestr) { FileStream fs = new FileStream(FilePath, FileMode.Create); //获得字节数组 byte[] data = System.Text.Encoding.Default.GetBytes(savestr); //开始写入 fs.Write(data, 0, data.Length); //清空缓冲区、关闭流 fs.Flush(); fs.Close(); } public void SaveFile2() { FileStream fs = new FileStream(FilePath , FileMode.Create); StreamWriter sw = new StreamWriter(fs); //开始写入 sw.Write("Hello World!!!!");             //清空缓冲区             sw.Flush();             //关闭流             sw.Close();             fs.Close();         }
    } }

调用方法：

           MyFile MyFile = new MyFile(Filepath);             string result = null;            // MyFile.SaveFile1(savastr);             MyFile.SaveFile2();             MyFile.ReadFile2();

c# txt文件的读写