获取给定月份和指定月份的开始和结束日期。给定的一周

问题描述：

如何在c＃4.0中获得给定年份（int），给定月份（int）和给定星期（int）的开始和结束日期{例如年：2011月：07周：04}？

How can I get the start and end date of a given year (int), given month (int), and given week (int) { example Year : 2011 Month: 07 week: 04 } in c# 4.0? Thanks in advance.

该年度的开始日期为2011年7月，该月的周号为04。

The Start Date of the Year 2011 Month 07 and the week number of the month is 04.

答

Google 是您的朋友。

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);
}

多年来您可以做类似的事情：

You can do something similar for years:

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

然后 week 需要使用CultureInfo.FirstDay（或某些情况下要设置为一周的第一天）国家/地区（星期一，有时是星期日）。

And week needs to use the CultureInfo.FirstDay (or whatever you want to set as the first day of a week, in some countries it's Monday, sometimes it's Sunday).

/// <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;
    }

获取给定月份和指定月份的开始和结束日期。给定的一周

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