获取给定周,给定月份和给定周的开始和结束日期

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){示例年份:2011月份:07周:04}的开始和结束日期？提前致谢.

2011年07月的开始日期和月份的周数是04.

Answer 1

谷歌是你的朋友.

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);
}

您可以多年来做类似的事情:

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

而本周需要使用CultureInfo.FirstDay(或者任何你想设置为一周的第一天,在一些国家,它是星期一,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;
    }