c# - 获取给定星期年份、给定月份和给定星期的开始和结束日期

Question

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

开始日期为 2011 年第 07 月，该月的周数为 04。

Answer 1

Google是你的 friend 。

月份:

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);
}

你可以做类似的事情很多年:

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

和week需要使用 CultureInfo.FirstDay(或任何您想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;
    }