我如何在c#中找到一周的开始(包括周日和周一),只知道当前时间?

喜欢的东西:

DateTime.Now.StartWeek(Monday);

当前回答

我能想到的最快方法是:

var sunday = DateTime.Today.AddDays(-(int)DateTime.Today.DayOfWeek);

如果您希望将一周中的任何一天作为您的开始日期,您所需要做的就是在结束时添加DayOfWeek值

var monday = DateTime.Today.AddDays(-(int)DateTime.Today.DayOfWeek + (int)DayOfWeek.Monday);

var tuesday = DateTime.Today.AddDays(-(int)DateTime.Today.DayOfWeek + (int)DayOfWeek.Tuesday);

其他回答

使用Fluent DateTime:

var monday = DateTime.Now.Previous(DayOfWeek.Monday);
var sunday = DateTime.Now.Previous(DayOfWeek.Sunday);

这将给你前一个星期天(我想):

DateTime t = DateTime.Now;
t -= new TimeSpan ((int) t.DayOfWeek, 0, 0, 0);

你可以使用优秀的Umbrella库:

using nVentive.Umbrella.Extensions.Calendar;
DateTime beginning = DateTime.Now.BeginningOfWeek();

然而,它们似乎已经将星期一存储为一周的第一天(参见属性nvent . umbrelga . extensions . calendar . defaultdatetimecalendarexextensions . weekbeginson),因此先前的本地化解决方案要好一些。不幸的。

编辑:仔细看看这个问题,雨伞似乎也能解决这个问题:

// Or DateTime.Now.PreviousDay(DayOfWeek.Monday)
DateTime monday = DateTime.Now.PreviousMonday(); 
DateTime sunday = DateTime.Now.PreviousSunday();

尽管值得注意的是,如果你在周一要求前一个周一,它会给你7天。但如果你使用BeginningOfWeek,这也是正确的,这似乎是一个错误:(。

我们喜欢简单的语句:获取当前文化中每周的第一天与当前日期之间的差值,然后从当前日期减去天数:

var weekStartDate = DateTime.Now.AddDays(-((int)now.DayOfWeek - (int)DateTimeFormatInfo.CurrentInfo.FirstDayOfWeek));

下面的方法应该返回所需的DateTime。周日为true,周一为false:

private DateTime getStartOfWeek(bool useSunday)
{
    DateTime now = DateTime.Now;
    int dayOfWeek = (int)now.DayOfWeek;

    if(!useSunday)
        dayOfWeek--;

    if(dayOfWeek < 0)
    {// day of week is Sunday and we want to use Monday as the start of the week
    // Sunday is now the seventh day of the week
        dayOfWeek = 6;
    }

    return now.AddDays(-1 * (double)dayOfWeek);
}