1. 獲取當前年月日時分秒:system.DateTime.Now
2. 獲取長日期:xxxx年xx月xx日
3. 獲取短日期:xxxx-xx-xx
4. 構造新日期:
DateTime now = DateTime.Now;
DateTime d1 = new DateTime(now.Year,now.Month,1);
5. 當前日期後推三天:
DateTime later = DateTime.Now.AddDays(3);
6. string轉DateTime
DateTime.parse(string str);