int time = 1234567891;(数据库中的存储的秒数)

DateTime BaseDateTime = new DateTime(1970, 1, 1);

DateTime ValidityDateTime = BaseDateTime.AddSeconds(timeSpan);

DateTime NowDateTime = DateTime.Now;

TimeSpan subtractSpan = NowDateTime - ValidityDateTime;

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.DateTime   dt1   =   DateTime.Now;   
 2   DateTime   dt2   =   DateTime.Now.AddDays(-7);   
 3   TimeSpan   ts   =   dt1   -   dt2;   
 4     
 5 int   days   =   ts.Days;   //dt1和dt2相差多少天
 6 
 7 eg2.
 8 //编辑月份和系统登录月份是否相等
 9 if(Convert.ToDateTime(DateTime.Now.ToShortDateString()).Month==Convert.ToDateTime(this.GetQueryString("sdate")).Month)
10      {
11       TimeSpan  ts=Convert.ToDateTime(DateTime.Now.ToShortDateString())-Convert.ToDateTime(this.GetQueryString("