C# 時間日期的擷取與比較

// 根據目前日期擷取 格式20160101類型的日期
        public static string DateString()
        {
            DateTime date = DateTime.Now;
            string tmp = "" + date.Year;
            tmp += (date.Month < 10 ? "0" : "") + date.Month;
            tmp += (date.Day < 10 ? "0" : "") + date.Day;

            return tmp;
        }

        // DateTime.Compare(time1, time2);
        // 從字元串擷取日期
        //string mytime = "2005-6-7 12:23:34";
        public static DateTime parseDate(string date)
        {
            IFormatProvider culture = new System.Globalization.CultureInfo("zh-CN", true);
            string[] expectedFormats = { "yyyy-MM-dd HH:mm:ss", "yyyy-MM-d HH:mm:ss", "yyyy-M-dd HH:mm:ss", "yyyy-M-dd HH:mm:ss" };
            DateTime dateTime = DateTime.ParseExact(date, expectedFormats, culture, System.Globalization.DateTimeStyles.AllowInnerWhite);

            return dateTime;
        }

        // 對兩個字元串日期進行比較
        public static int cmp(string str1, string str2)
        {
            //DateTime date1 = Tool.parseDate("2005-6-07 12:23:34");
            //DateTime date2 = Tool.parseDate("2005-07-07 12:23:34");
            //return -1

            DateTime date1 = Tool.parseDate(str1);
            DateTime date2 = Tool.parseDate(str2);

            return DateTime.Compare(date1, date2);
        }