c#循环两个日期之前的时间

for (DateTime dt = startDate; dt < endDate; dt = dt.AddMonths(1))
{
    var year = date.Year;
    var month= date.Month;
}    

时间戳

    public static class DateTimeUtil
    {
        /// <summary>
        /// 时间戳计时开始时间
        /// </summary>
        private static DateTime timeStampStartTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

        /// <summary>
        /// DateTime转换为10位时间戳（单位：秒）
        /// </summary>
        /// <param name="dateTime"> DateTime</param>
        /// <returns>10位时间戳（单位：秒）</returns>
        public static long DateTimeToTimeStamp(DateTime dateTime)
        {
            return (long)(dateTime.ToUniversalTime() - timeStampStartTime).TotalSeconds;
        }

        /// <summary>
        /// DateTime转换为13位时间戳（单位：毫秒）
        /// </summary>
        /// <param name="dateTime"> DateTime</param>
        /// <returns>13位时间戳（单位：毫秒）</returns>
        public static long DateTimeToLongTimeStamp(DateTime dateTime)
        {
            return (long)(dateTime.ToUniversalTime() - timeStampStartTime).TotalMilliseconds;
        }

        /// <summary>
        /// 10位时间戳（单位：秒）转换为DateTime
        /// </summary>
        /// <param name="timeStamp">10位时间戳（单位：秒）</param>
        /// <returns>DateTime</returns>
        public static DateTime TimeStampToDateTime(long timeStamp)
        {
            return timeStampStartTime.AddSeconds(timeStamp).ToLocalTime();
        }

        /// <summary>
        /// 13位时间戳（单位：毫秒）转换为DateTime
        /// </summary>
        /// <param name="longTimeStamp">13位时间戳（单位：毫秒）</param>
        /// <returns>DateTime</returns>
        public static DateTime LongTimeStampToDateTime(long longTimeStamp)
        {
            return timeStampStartTime.AddMilliseconds(longTimeStamp).ToLocalTime();
        }
    }


    public static partial class Ext
    {

        /// <summary>
        /// 时间工具类
        /// </summary>
    
        /// <summary>
        /// 获取格式化字符串，带时分秒，格式："yyyy-MM-dd HH:mm:ss"
        /// </summary>
        /// <param name="dateTime">日期</param>
        /// <param name="isRemoveSecond">是否移除秒</param>
        public static string ToDateTimeString(this DateTime dateTime, bool isRemoveSecond = false)
        {
            if (isRemoveSecond)
                return dateTime.ToString("yyyy-MM-dd HH:mm");
            return dateTime.ToString("yyyy-MM-dd HH:mm:ss");
        }

        /// <summary>
        /// 获取格式化字符串，带时分秒，格式："yyyy-MM-dd HH:mm:ss"
        /// </summary>
        /// <param name="dateTime">日期</param>
        /// <param name="isRemoveSecond">是否移除秒</param>
        public static string ToDateTimeString(this DateTime? dateTime, bool isRemoveSecond = false)
        {
            if (dateTime == null)
                return string.Empty;
            return ToDateTimeString(dateTime.Value, isRemoveSecond);
        }

        /// <summary>
        /// 获取格式化字符串，不带时分秒，格式："yyyy-MM-dd"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToDateString(this DateTime dateTime)
        {
            return dateTime.ToString("yyyy-MM-dd");
        }
        /// <summary>
        /// 获取格式化字符串，不带时分秒，格式："yyyy-MM-dd"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToDateString()
        {
            return DateTime.Now.ToString("yyyy-MM-dd");
        }

        /// <summary>
        /// 获取格式化字符串，不带时分秒，格式："yyyy-MM-dd"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToDateString(this DateTime? dateTime)
        {
            if (dateTime == null)
                return string.Empty;
            return ToDateString(dateTime.Value);
        }

        /// <summary>
        /// 获取格式化字符串，不带年月日，格式："HH:mm:ss"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToTimeString(this DateTime dateTime)
        {
            return dateTime.ToString("HH:mm:ss");
        }

        /// <summary>
        /// 获取格式化字符串，不带年月日，格式："HH:mm:ss"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToTimeString(this DateTime? dateTime)
        {
            if (dateTime == null)
                return string.Empty;
            return ToTimeString(dateTime.Value);
        }

        /// <summary>
        /// 获取格式化字符串，带毫秒，格式："yyyy-MM-dd HH:mm:ss.fff"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToMillisecondString(this DateTime dateTime)
        {
            return dateTime.ToString("yyyy-MM-dd HH:mm:ss.fff");
        }

        /// <summary>
        /// 获取格式化字符串，带毫秒，格式："yyyy-MM-dd HH:mm:ss.fff"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToMillisecondString(this DateTime? dateTime)
        {
            if (dateTime == null)
                return string.Empty;
            return ToMillisecondString(dateTime.Value);
        }

        /// <summary>
        /// 获取格式化字符串，不带时分秒，格式："yyyy年MM月dd日"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToChineseDateString(this DateTime dateTime)
        {
            return string.Format("{0}年{1}月{2}日", dateTime.Year, dateTime.Month, dateTime.Day);
        }

        /// <summary>
        /// 获取格式化字符串，不带时分秒，格式："yyyy年MM月dd日"
        /// </summary>
        /// <param name="dateTime">日期</param>
        public static string ToChineseDateString(this DateTime? dateTime)
        {
            if (dateTime == null)
                return string.Empty;
            return ToChineseDateString(dateTime.SafeValue());
        }

        /// <summary>
        /// 获取格式化字符串，带时分秒，格式："yyyy年MM月dd日 HH时mm分"
        /// </summary>
        /// <param name="dateTime">日期</param>
        /// <param name="isRemoveSecond">是否移除秒</param>
        public static string ToChineseDateTimeString(this DateTime dateTime, bool isRemoveSecond = false)
        {
            StringBuilder result = new StringBuilder();
            result.AppendFormat("{0}年{1}月{2}日", dateTime.Year, dateTime.Month, dateTime.Day);
            result.AppendFormat(" {0}时{1}分", dateTime.Hour, dateTime.Minute);
            if (isRemoveSecond == false)
                result.AppendFormat("{0}秒", dateTime.Second);
            return result.ToString();
        }

        /// <summary>
        /// 获取格式化字符串，带时分秒，格式："yyyy年MM月dd日 HH时mm分"
        /// </summary>
        /// <param name="dateTime">日期</param>
        /// <param name="isRemoveSecond">是否移除秒</param>
        public static string ToChineseDateTimeString(this DateTime? dateTime, bool isRemoveSecond = false)
        {
            if (dateTime == null)
                return string.Empty;
            return ToChineseDateTimeString(dateTime.Value);
        }


    }

对json的一些操作

    public static class Json
    {
        public static object ToJson(this string Json)
        {
            return Json == null ? null : JsonConvert.DeserializeObject(Json);
        }
        public static string ToJson(this object obj)
        {
            var timeConverter = new IsoDateTimeConverter { DateTimeFormat = "yyyy-MM-dd HH:mm:ss" };
            return JsonConvert.SerializeObject(obj, timeConverter);
        }
        public static string ToJson(this object obj, string datetimeformats)
        {
            var timeConverter = new IsoDateTimeConverter { DateTimeFormat = datetimeformats };
            return JsonConvert.SerializeObject(obj, timeConverter);
        }
        public static T ToObject<T>(this string Json)
        {
            return Json == null ? default(T) : JsonConvert.DeserializeObject<T>(Json);
        }
        public static List<T> ToList<T>(this string Json)
        {
            return Json == null ? null : JsonConvert.DeserializeObject<List<T>>(Json);
        }
        public static DataTable ToTable(this string Json)
        {
            return Json == null ? null : JsonConvert.DeserializeObject<DataTable>(Json);
        }
        public static JObject ToJObject(this string Json)
        {
            return Json == null ? JObject.Parse("{}") : JObject.Parse(Json.Replace("&nbsp;", ""));
        }
    }