C#时间
string a = ((DateTime.Now.ToUniversalTime().Ticks - 621355968000000000) / 1000).ToString();
毫秒时间戳
(long)(DateTime.Now.ToUniversalTime() - new DateTime(1970, 1, 1)).TotalSeconds
秒时间戳，long类型
二、Convert.ToDateTime(string)
string格式有要求，必须是yyyy-MM-dd hh:mm:ss
三、Convert.ToDateTime(string, IFormatProvider)
DateTime dt;
DateTimeFormatInfo dtFormat = new System.GlobalizationDateTimeFormatInfo();
dtFormat.ShortDatePattern = "yyyy/MM/dd";
dt = Convert.ToDateTime("2011/05/26", dtFormat);