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);
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
周一
DateTime startAtMonday = DateTime.Now.AddDays(DayOfWeek.Monday - DateTime.Now.DayOfWeek);
在周日
DateTime startAtSunday = DateTime.Now.AddDays(DayOfWeek.Sunday- DateTime.Now.DayOfWeek);
其他回答
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);
使用扩展方法:
public static class DateTimeExtensions
{
public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek)
{
int diff = (7 + (dt.DayOfWeek - startOfWeek)) % 7;
return dt.AddDays(-1 * diff).Date;
}
}
可以这样使用:
DateTime dt = DateTime.Now.StartOfWeek(DayOfWeek.Monday);
DateTime dt = DateTime.Now.StartOfWeek(DayOfWeek.Sunday);
从Compile This' answer开始,使用以下方法获取一周中任何一天的日期:
public static DateTime GetDayOfWeek(DateTime dateTime, DayOfWeek dayOfWeek)
{
var monday = dateTime.Date.AddDays((7 + (dateTime.DayOfWeek - DayOfWeek.Monday) % 7) * -1);
var diff = dayOfWeek - DayOfWeek.Monday;
if (diff == -1)
{
diff = 6;
}
return monday.AddDays(diff);
}
虽然很丑,但至少还能说出正确的日期
由系统设置一周开始:
public static DateTime FirstDateInWeek(this DateTime dt)
{
while (dt.DayOfWeek != System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat.FirstDayOfWeek)
dt = dt.AddDays(-1);
return dt;
}
没有:
public static DateTime FirstDateInWeek(this DateTime dt, DayOfWeek weekStartDay)
{
while (dt.DayOfWeek != weekStartDay)
dt = dt.AddDays(-1);
return dt;
}
我尝试了几次,但我没有解决从星期一开始的一周的问题,导致我的下一个星期一是星期天。所以我对它做了一些修改,让它与下面的代码一起工作:
int delta = DayOfWeek.Monday - DateTime.Now.DayOfWeek;
DateTime monday = DateTime.Now.AddDays(delta == 1 ? -6 : delta);
return monday;