获取给定周年、给定月份和日期的开始和结束日期给定的一周

Question

如何在 c# 4.0 中获取给定年份 (int)、给定月份 (int) 和给定周 (int) { example Year : 2011 Month: 07 week: 04 } 的开始和结束日期？提前致谢。

2011 年的开始日期为 07 月，该月的周数为 04。

Answer 1

你也可以用

DateTime.DaysInMonth(int year,int month);

它来弄清楚。这几周将会更加困难。

Answer 2

日期时间计算，因为这些有点棘手，通过一些假设我可以想出这个

//assign it to the first day of the month
DateTime getweek = new DateTime(2011, 4, 1);
// say the week starts on a Sunday
while (getweek.DayOfWeek != DayOfWeek.Sunday)
      getweek = getweek.AddDays(1);
DateTimeFormatInfo info = DateTimeFormatInfo.CurrentInfo;            
Calendar cal = info.Calendar;
//Now you are on the first week add 3 more to move to the Fourth week
DateTime start = cal.AddWeeks(getweek, 3); // 24 April 2011
DateTime end = start.AddDays(6); // 30 April 2011

Answer 3

Google 是您的朋友。

几个月：

public DateTime FirstDayOfMonthFromDateTime(DateTime dateTime)
{
   return new DateTime(dateTime.Year, dateTime.Month, 1);
}


public DateTime LastDayOfMonthFromDateTime(DateTime dateTime)
{
   DateTime firstDayOfTheMonth = new DateTime(dateTime.Year, dateTime.Month, 1);
   return firstDayOfTheMonth.AddMonths(1).AddDays(-1);
}

您可以在几年内做类似的事情：

   DateTime time = new DateTime(2011,1,1);
   time.AddYears(1).AddDays(-1);

并且 week 需要使用 CultureInfo.FirstDay （或任何您想要设置为一周的第一天，在某些国家/地区是星期一，有时是星期日）。

/// <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 4

不确定，但这就是你想要的吗？

var weekStart = new DateTime(year, month, 1).AddDays(week * 7);
var weekEnd = weekStart.AddDays(6);

Answer 5

假设您从第一周开始：

var startDate = new DateTime(year, month, 1).AddDays((week - 1) * 7);
var endDate = startDate.AddDays(6);