using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.IO;namespace fileIO{    class Program    {        static void Main(string[] args)        {            string filename =AppDomain.CurrentDomain.BaseDirectory+ "companyUpdateLog.txt";            if (File.Exists(filename))            {                string time=ReadLog(filename);                if (time != "") {                    DateTime dt;                    if (DateTime.TryParse(time, out dt)) {                        DateTime dtnow = DateTime.Now;                        int days = (dtnow - dt).Days;                        if (days == 7)                        {                            //开始更新                            Console.WriteLine("正在更新");                            WriteLog(filename, dtnow.ToString("yyyy-MM-dd HH:mm:ss"));                        }                        else {                            Console.WriteLine("无需更新");                        }                    }                }            }            else {                DateTime dtnow = DateTime.Now;                //开始更新                Console.WriteLine("文件不存在时候：正在更新");                WriteLog(filename, dtnow.ToString("yyyy-MM-dd HH:mm:ss"));            }                    Console.ReadLine();        }      public static  void WriteLog(string path,string text) {          using (FileStream file = new FileStream(path, FileMode.OpenOrCreate))            {                StreamWriter sw = new StreamWriter(file);                sw.Write(text);                sw.Close();            }        }      public static string ReadLog(string path)      {          string a="";          using (FileStream file = new FileStream(path, FileMode.Open))          {              StreamReader sw = new StreamReader(file);              a=sw.ReadToEnd();              sw.Close();          }          return a;      }