c# 读写文本文件，二进制文件

/// <summary>
        /// 读取二进制文件
        /// </summary>
        /// <param name="filename"></param>
        private void ReadBinaryFiles(string filename)
        {
            FileStream filesstream = new FileStream(filename, FileMode.Create);
            BinaryWriter objBinaryWriter = new BinaryWriter(filesstream);
            for (int index = 0; index < 20; index++)
            {
                objBinaryWriter.Write((int)index);
            }
            objBinaryWriter.Close();
            filesstream.Close();
        }
        /// <summary>
        /// 写入二进制文件
        /// </summary>
        /// <param name="filepath"></param>
        private void WriteBinaryFiles(string filepath)
        {
            if (!File.Exists(filepath))
            {
                //文件不存在
            }
            else
            {
                FileStream filestream = new FileStream(filepath, FileMode.Open, FileAccess.Read);
                BinaryReader objBinaryReader = new BinaryReader(filestream);
                try
                {
                    while (true)
                    {
                        //objBinaryReader.ReadInt32();
                    }
                }
                catch (Exception ex)
                {
                    //已到文件结尾
                }
            }
        }

File 类：
Create(string FilePath)
在指定路径下创建具有指定名称的文件。此方法返回一个FileStream 对象
OpenRead(string FilePath)
打开一个现有文件来读取数据
AppendText(string FilePah)
允许向文本添加文本
Copy(string SourceFilePath,string DestinationPath)
按指定的路径将源文件的内容复制到目标文件中。如果目标不存在，则在指定的路径中以指定的名称新建一个文件
Delete(string filePath)
删除指定路径的文件
Exists(string filePath)
验证指定路径是否存在具有指定名称的文件。该方法返回一个布尔值

/// <summary>
        /// 写入文件
        /// </summary>
        /// <param name="filename"></param>
        /// <param name="filecontent"></param>
        private void SaveFiles(string filename,string filecontent)
        {
            FileStream fs;
            try
            {
                fs = File.Create(filename);
            }
            catch (Exception ex)
            {
                throw ex;
            }
            byte[] content = new UTF8Encoding(true).GetBytes(filecontent);
            try
            {
                fs.Write(content, 0, content.Length);
                fs.Flush();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                fs.Close();
            }
        }
        /// <summary>
        /// 保存文件
        /// </summary>
        /// <param name="path"></param>
        private void ReadFiles(string path)
        {
            try
            {
                if (!File.Exists(path))
                {
                    //文件不存在
                }
                else
                {
                    //打开流读取
                    FileStream fs = File.OpenRead(path);
                    //创建一个byte 数组以读取数据
                    byte[] arr = new byte[100];
                    UTF8Encoding data = new UTF8Encoding(true);
                    //继续读完文件的所有数据
                    while (fs.Read(arr, 0, arr.Length) > 0)
                    {
                        //data.GetString(arr);
                    }
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }