c# - 在 c# 中获取 GetWeekOfYear 的日期？

Question

我有这个功能，它给了我（当前日期） - 它的周数：

因此对于 ：DateTime(2009,1,1)

 CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(new DateTime(2009,1,1), CalendarWeekRule.FirstDay, DayOfWeek.Sunday).Dump();

回答 ：1

和：DateTime(2009,1,4)

回答 ：2

现在，我需要一个函数，它给我这个值的 startDate && endDate：

so for week #1 -> 1/1/2009   ---> 1/3/2009
so for week #2 -> 1/4/2009   ---> 1/10/2009

因此：我有一个函数可以给我指定日期的星期数。但本周跨越x---> y

我需要那些 x 和 y。

谢谢。

ps - 我一直在寻找这样的函数，但没有找到。:-(

Answer 1

我曾经使用过这篇文章评论中描述的一种方法 http://joelabrahamsson.com/entry/getting-the-first-date-in-a-week-with-c-sharp

Answer 2

using System;
using System.Globalization;

public static class FirstDayOfWeekUtility
{
    /// <summary>
    /// Returns the first day of the week that the specified
    /// date is in using the current culture. 
    /// </summary>
    public static DateTime GetFirstDayOfWeek(DateTime dayInWeek)
    {
        CultureInfo defaultCultureInfo = CultureInfo.CurrentCulture;
        return GetFirstDateOfWeek(dayInWeek, defaultCultureInfo);
    }

    /// <summary>
    /// Returns the first day of the week that the specified date 
    /// is in. 
    /// </summary>
    public static DateTime GetFirstDayOfWeek(DateTime dayInWeek, CultureInfo cultureInfo)
    {
        DayOfWeek firstDay = cultureInfo.DateTimeFormat.FirstDayOfWeek;
        DateTime firstDayInWeek = dayInWeek.Date;
        while (firstDayInWeek.DayOfWeek != firstDay)
            firstDayInWeek = firstDayInWeek.AddDays(-1);

            return firstDayInWeek;
    }
}

Answer 3

要获取一周中的第一天，按日期：

static DateTime GetFirstDayOfWeek(DateTime date)
{
    var firstDayOfWeek = date.AddDays(-((date.DayOfWeek - DayOfWeek.Sunday + 7) % 7));
    if (firstDayOfWeek.Year != date.Year)
        firstDayOfWeek = new DateTime(date.Year, 1, 1);
    return firstDayOfWeek;
}

一周的最后一天的工作方式相同：

static DateTime GetLastDayOfWeek(DateTime date)
{
    var lastDayOfWeek = date.AddDays((DayOfWeek.Saturday - date.DayOfWeek + 7) % 7);
    if (lastDayOfWeek.Year != date.Year)
        lastDayOfWeek = new DateTime(date.Year, 12, 31);
    return lastDayOfWeek;
}

Royi 的补充（最终）：

扩展方法，它为您提供单个日期的所有详细信息（周详细信息）：ps 星期的第一天 = 星期日。

   public class DateTimeSpan
    {
        public DateTime WeekStartDate;
        public DateTime WeekEndDate;
        public DateTime MonthStartDate;
        public DateTime MonthEndDate;
        public DateTime YearStartDate;
        public DateTime YearEndDate;
        public int WeekNum;

    }

    public static DateTimeSpan TimeProperties(this DateTime str)
    {
        if (str == null) return null;
        DateTimeSpan dts = new DateTimeSpan();
        dts.WeekNum=     CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(str, CalendarWeekRule.FirstDay, DayOfWeek.Sunday);
        dts.WeekStartDate = GetFirstDayOfWeek(str);
        dts.WeekEndDate = GetLAstDayOfWeek(str);
        dts.MonthStartDate = new DateTime(str.Year, str.Month, 1);
        int numberOfDays = DateTime.DaysInMonth(str.Year, str.Month);
        DateTime last = new DateTime(str.Year, str.Month, numberOfDays);
        dts.MonthEndDate = last;
        dts.YearStartDate = new DateTime(str.Year, 1, 1);
        numberOfDays = DateTime.DaysInMonth(str.Year, 12);
        last = new DateTime(str.Year, 12, numberOfDays);
        dts.YearEndDate = last;

        return dts;
    }


    static DateTime GetFirstDayOfWeek(DateTime date)
    {
        var firstDayOfWeek = date.AddDays(-((date.DayOfWeek - DayOfWeek.Sunday + 7) % 7));
        if (firstDayOfWeek.Year != date.Year)
            firstDayOfWeek = new DateTime(date.Year, 1, 1);
        return firstDayOfWeek;
    }

    static DateTime GetLAstDayOfWeek(DateTime date)
    {
        var firstDayOfWeek = date.AddDays(((DayOfWeek.Saturday - date.DayOfWeek + 7) % 7));
        if (firstDayOfWeek.Year != date.Year)
            firstDayOfWeek = new DateTime(date.Year, 12, 31);
        return firstDayOfWeek;
    }