日期时间处理函数收集

using System;
namespace qminoa.Common
{
    /// <summary >
    /// 日期处理函数包
    /// </summary >
    public class DateUtil
    {
        //构造函数
        public DateUtil()
        {
        }

        /// <summary >返回本年有多少天</summary >
        /// <param name="iYear" >年份</param >
        /// <returns >本年的天数</returns >
        public static int GetDaysOfYear(int iYear)
        {
            int cnt = 0;
            if (IsRuYear(iYear))
            {
                cnt = 366;//闰年多 1 天 即：2 月为 29 天
            }
            else
            {
                cnt = 365;//--非闰年少1天 即：2 月为 28 天
            }
            return cnt;
        }

        /// <summary >本年有多少天</summary >
        /// <param name="dt" >日期</param >
        /// <returns >本天在当年的天数</returns >
        public static int GetDaysOfYear(DateTime idt)
        {
            int n;
            //取得传入参数的年份部分，用来判断是否是闰年
            n = idt.Year;
            if (IsRuYear(n))
            {
                return 366;//闰年多 1 天 即：2 月为 29 天
            }
            else
            {
                return 365; //--非闰年少1天 即：2 月为 28 天
            }
        }

        /// <summary >本月有多少天</summary >
        /// <param name="iYear" >年</param >
        /// <param name="Month" >月</param >
        /// <returns >天数</returns >
        public static int GetDaysOfMonth(int iYear, int Month)
        {
            int days = 0;
            switch (Month)
            {
                case 1:
                    days = 31;
                    break;
                case 2:
                    if (IsRuYear(iYear))
                    {
                        days = 29;//闰年多 1 天 即：2 月为 29 天
                    }
                    else
                    {
                        days = 28;//--非闰年少1天 即：2 月为 28 天
                    }
                    break;
                case 3:
                    days = 31;
                    break;
                case 4:
                    days = 30;
                    break;
                case 5:
                    days = 31;
                    break;
                case 6:
                    days = 30;
                    break;
                case 7:
                    days = 31;
                    break;
                case 8:
                    days = 31;
                    break;
                case 9:
                    days = 30;
                    break;
                case 10:
                    days = 31;
                    break;
                case 11:
                    days = 30;
                    break;
                case 12:
                    days = 31;
                    break;
            }
            return days;
        }

        /// <summary >本月有多少天</summary >
        /// <param name="dt" >日期</param >
        /// <returns >天数</returns >
        public static int GetDaysOfMonth(DateTime dt)
        {
            //--------------------------------//
            //--从dt中取得当前的年，月信息  --//
            //--------------------------------//
            int year, month, days = 0;
            year = dt.Year;
            month = dt.Month;
            //--利用年月信息，得到当前月的天数信息。
            switch (month)
            {
                case 1:
                    days = 31;
                    break;
                case 2:
                    if (IsRuYear(year))
                    {
                        days = 29;  //闰年多 1 天 即：2 月为 29 天
                    }
                    else
                    {
                        days = 28;  //--非闰年少1天 即：2 月为 28 天
                    }
                    break;
                case 3:
                    days = 31;
                    break;
                case 4:
                    days = 30;
                    break;
                case 5:
                    days = 31;
                    break;
                case 6:
                    days = 30;
                    break;
                case 7:
                    days = 31;
                    break;
                case 8:
                    days = 31;
                    break;
                case 9:
                    days = 30;
                    break;
                case 10:
                    days = 31;
                    break;
                case 11:
                    days = 30;
                    break;
                case 12:
                    days = 31;
                    break;
            }
            return days;
        }

        /// <summary >返回当前日期的星期名称</summary >
        /// <param name="dt" >日期</param >
        /// <returns >星期名称</returns >
        public static string GetWeekNameOfDay(DateTime idt)
        {
            string dt, week = "";
            dt = idt.DayOfWeek.ToString();
            switch (dt)
            {
                case "Mondy":
                    week = "星期一";
                    break;
                case "Tuesday":
                    week = "星期二";
                    break;
                case "Wednesday":
                    week = "星期三";
                    break;
                case "Thursday":
                    week = "星期四";
                    break;
                case "Friday":
                    week = "星期五";
                    break;
                case "Saturday":
                    week = "星期六";
                    break;
                case "Sunday":
                    week = "星期日";
                    break;
            }
            return week;
        }

        /// <summary >返回当前日期的星期编号</summary >
        /// <param name="dt" >日期</param >
        /// <returns >星期数字编号</returns >
        public static string GetWeekNumberOfDay(DateTime idt)
        {
            string dt, week = "";
            dt = idt.DayOfWeek.ToString();
            switch (dt)
            {
                case "Mondy":
                    week = "1";
                    break;
                case "Tuesday":
                    week = "2";
                    break;
                case "Wednesday":
                    week = "3";
                    break;
                case "Thursday":
                    week = "4";
                    break;
                case "Friday":
                    week = "5";
                    break;
                case "Saturday":
                    week = "6";
                    break;
                case "Sunday":
                    week = "7";
                    break;

            }
            return week;
        }

        /// <summary >返回两个日期之间相差的天数</summary >
        /// <param name="dt" >两个日期参数</param >
        /// <returns >天数</returns >
        public static int DiffDays(DateTime dtfrm, DateTime dtto)
        {
            int diffcnt = 0;
            //diffcnt = dtto- dtfrm ;
            return diffcnt;
        }

        /// <summary >判断当前日期所属的年份是否是闰年，私有函数</summary >
        /// <param name="dt" >日期</param >
        /// <returns >是闰年：True ，不是闰年：False</returns >
        private static bool IsRuYear(DateTime idt)
        {
            //形式参数为日期类型 
            //例如：2003-12-12
            int n;
            n = idt.Year;
            if ((n % 400 == 0) || (n % 4 == 0 && n % 100 != 0))
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        /// <summary >判断当前年份是否是闰年，私有函数</summary >
        /// <param name="dt" >年份</param >
        /// <returns >是闰年：True ，不是闰年：False</returns >
        private static bool IsRuYear(int iYear)
        {
            //形式参数为年份 例如：2003
            int n;
            n = iYear;
            if ((n % 400 == 0) || (n % 4 == 0 && n % 100 != 0))
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        /// <summary >
        /// 将输入的字符串转化为日期。如果字符串的格式非法，则返回当前日期。
        /// </summary >
        /// <param name="strInput" >输入字符串</param >
        /// <returns >日期对象</returns >
        public static DateTime ConvertStringToDate(string strInput)
        {
            DateTime oDateTime;
            try
            {
                oDateTime = DateTime.Parse(strInput);
            }
            catch (Exception)
            {
                oDateTime = DateTime.Today;
            }

            return oDateTime;
        }

        /// <summary >
        /// 将日期对象转化为格式字符串
        /// </summary >
        /// <param name="oDateTime" >日期对象</param >
        /// <param name="strFormat" >
        /// 格式：
        ///     "SHORTDATE"===短日期
        ///     "LONGDATE"==长日期
        ///     其它====自定义格式
        /// </param >
        /// <returns >日期字符串</returns >
        public static string ConvertDateToString(DateTime oDateTime, string strFormat)
        {
            string strDate = "";
            try
            {
                switch (strFormat.ToUpper())
                {
                    case "SHORTDATE":
                        strDate = oDateTime.ToShortDateString();
                        break;
                    case "LONGDATE":
                        strDate = oDateTime.ToLongDateString();
                        break;
                    default:
                        strDate = oDateTime.ToString(strFormat);
                        break;
                }
            }
            catch (Exception)
            {
                strDate = oDateTime.ToShortDateString();
            }

            return strDate;
        }

        /// <summary >
        /// 判断是否为合法日期，必须大于1800年1月1日
        /// </summary >
        /// <param name="strDate" >输入日期字符串</param >
        /// <returns >True/False</returns >
        public static bool IsDateTime(string strDate)
        {
            try
            {
                DateTime oDate = DateTime.Parse(strDate);
                if (oDate.CompareTo(DateTime.Parse("1800-1-1"))  > 0)
                    return true;
                else
                    return false;
            }
            catch (Exception)
            {
                return false;
            }
        }
    }
}