class Program
    {   
        /// <summary>
        /// 写入文件
        /// </summary>
        /// <param name="args"></param>
        static void Main(string[] args)
        {
            Console.WriteLine("请输入文件名：");
            string filename = Console.ReadLine();
            FileStream fs;//声明FileStream对象
            try
            {
                fs = new FileStream(filename, FileMode.Create);
                BinaryWriter bw = new BinaryWriter(fs);
                bw.Write('a');
                bw.Write("liuxiaoxiaoying");
                bw.Write(123456);
                bw.Write(456.789);
                Console.WriteLine("成功写入");
                bw.Close();
                fs.Close();
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
            }
            Console.ReadKey();
        }
    }
但写入进去的只有字符，和字符串，数字进去后是乱码，但书上写的是可以写入数字