.net 获取上周一的日期
我想知道本周星期一的日期。这接近正确吗.net 获取上周一的日期,.net,vb.net,date,days,date-difference,.net,Vb.net,Date,Days,Date Difference,我想知道本周星期一的日期。这接近正确吗 Dim MondayOfCurrentWeek As Date = Date.Today - Date.Today.DayOfWeek + 1 据我所知,AyOfWeek索引为: 1 = Monday 2 = Tuesday 3 = Wednesday 4 = Thursday 5 = Friday 6 = Saturday 0 = Sunday 因此,如果今天是星期四,我会得到: Dim MondayOfCurrentWeek As Date = D
Dim MondayOfCurrentWeek As Date = Date.Today - Date.Today.DayOfWeek + 1
据我所知,AyOfWeek索引为:
1 = Monday
2 = Tuesday
3 = Wednesday
4 = Thursday
5 = Friday
6 = Saturday
0 = Sunday
因此,如果今天是星期四,我会得到:
Dim MondayOfCurrentWeek As Date = Date - 4 + 1
这等于
Date - 3
对我来说似乎是对的
或者说我完全错了?这是一种非常简单的替代方法,虽然性能可能不太好,但确实避免了任何基于算术的错误:
Dim monday As Date = Date.Today
While (monday.DayOfWeek <> DayOfWeek.Monday)
monday = monday.AddDays(-1)
End While
Dim monday As Date=Date.Today
而(星期一。星期五。星期一)
星期一=星期一。添加天数(-1)
结束时
这可以很容易地扩展为一个函数来处理一周中的任何一天。除非这是一段非常大容量的代码,否则性能会很好。这应该可以满足您的需要。它从提供的日期开始查找上一个星期一。没有循环,因此速度很快,不依赖枚举值进行算术调整,因此在枚举值发生变化时不会中断:
Public Shared Function PreviousMonday(ByVal dateValue As DateTime) As DateTime
Dim dayOffset As Integer
Select Case dateValue.DayOfWeek
Case DayOfWeek.Sunday : dayOffset = 6
Case DayOfWeek.Monday : dayOffset = 0
Case DayOfWeek.Tuesday : dayOffset = 1
Case DayOfWeek.Wednesday : dayOffset = 2
Case DayOfWeek.Thursday : dayOffset = 3
Case DayOfWeek.Friday : dayOffset = 4
Case DayOfWeek.Saturday : dayOffset = 5
End Select
Return dateValue.AddDays(-1 * dayOffset)
End Function
如果您正在寻找前一周的周一到周日范围,那么您可以使用这些函数(Matt Wilko答案的修改版本)获得它们
它是C#,但有一个,它有一个很好的功能,你可以在一周中的任何一天使用。另一方面,虽然枚举不应该在未来的版本中更改,但它们总是有可能更改。我对基于枚举值执行算术非常谨慎。他究竟为什么要使用枚举?一周中的几天是内置在.NET框架中的。@Hypenate.FWIW-星期天不是0吗?@Matt确实如此。但是OP是在周一之后,而不是开始日。实际上他是在本周的周一之后,而不是前一周Monday@Matt啊,是的-我知道你得到了什么atI没有详细说明我的问题。我想得不够透彻。但是前一个星期一,这个答案正是我所需要的。一般来说,如果答案中包含了对代码意图的解释,以及在不介绍其他代码的情况下解决问题的原因,那么答案会更有帮助。
Public Shared Function PreviousMonday(ByVal dateValue As Date) As Date
Dim dayOffset As Integer
Select Case dateValue.DayOfWeek
Case DayOfWeek.Sunday : dayOffset = -13
Case DayOfWeek.Monday : dayOffset = -7
Case DayOfWeek.Tuesday : dayOffset = -8
Case DayOfWeek.Wednesday : dayOffset = -9
Case DayOfWeek.Thursday : dayOffset = -10
Case DayOfWeek.Friday : dayOffset = -11
Case DayOfWeek.Saturday : dayOffset = -12
End Select
Return dateValue.AddDays(dayOffset)
End Function
Public Shared Function PreviousSunday(ByVal dateValue As Date) As Date
Dim dayOffset As Integer
Select Case dateValue.DayOfWeek
Case DayOfWeek.Sunday : dayOffset = -7
Case DayOfWeek.Monday : dayOffset = -1
Case DayOfWeek.Tuesday : dayOffset = -2
Case DayOfWeek.Wednesday : dayOffset = -3
Case DayOfWeek.Thursday : dayOffset = -4
Case DayOfWeek.Friday : dayOffset = -5
Case DayOfWeek.Saturday : dayOffset = -6
End Select
Return dateValue.AddDays(dayOffset)
End Function
var now = DateTime.Now; //17.09.2020 19:15:49
int dayInWeek = (int)now.DayOfWeek; //4
var previousMonday = now.AddDays(-(((dayInWeek + 6) % 7) + 7)); //-10
var previousSunday= previousMonday.AddDays(6); //-4
Console.WriteLine(previousMonday); //07.09.2020 19:15:49
Console.WriteLine(previousSunday); //13.09.2020 19:15:49