如何更改哪一天是一周中的第一天？

Question

我需要在asp.net中更改一周的第一天，即我希望星期六成为本周的第一天。

例如，下面的代码应该在星期一返回3：

(int)DateTime.Now.DayOfWeek 

Answer 1

我想你只需要你的使用（DayOfWeek Enumeration）改变文化。

Thread.CurrentThread.CurrentCulture = New CultureInfo("ar-EG") 

Answer 2

使用以下代码更改asp.net应用程序中的第一个星期几。

CultureInfo _culture = (CultureInfo)CultureInfo.CurrentCulture.Clone(); 
CultureInfo _uiculture = (CultureInfo)CultureInfo.CurrentUICulture.Clone(); 

_culture.DateTimeFormat.FirstDayOfWeek = DayOfWeek.Saturday; 
_uiculture.DateTimeFormat.FirstDayOfWeek = DayOfWeek.Saturday; 

System.Threading.Thread.CurrentThread.CurrentCulture = _culture; 
System.Threading.Thread.CurrentThread.CurrentUICulture = _uiculture; 

Answer 3

不能影响的DateTime.DayOfWeek的值，因为这是一种类型的System.DayOfWeek这是枚举（即，的值是恒定的）。 System.DayOfWeek的定义在下面的代码块中。因此，如果您想在周一和周六将DayOfWeek视为3这一周的第一天，那么我必须假设您需要基于1到7的编号系统。在这种情况下，您可以使用((int)DateTime.Now.DayOfWeek+1) % 7 + 1来获得您想要的号码。如果你不需要这个计算，最好只将DateTime.Now.DayOfWeek的值与它的枚举常量（例如if(DateTime.Now.DayOfWeek == DayOfWeek.Monday) ...）进行比较。

// Summary: 
//  Specifies the day of the week. 
[Serializable] 
[ComVisible(true)] 
public enum DayOfWeek 
{ 
    // Summary: 
    //  Indicates Sunday. 
    Sunday = 0, 
    // 
    // Summary: 
    //  Indicates Monday. 
    Monday = 1, 
    // 
    // Summary: 
    //  Indicates Tuesday. 
    Tuesday = 2, 
    // 
    // Summary: 
    //  Indicates Wednesday. 
    Wednesday = 3, 
    // 
    // Summary: 
    //  Indicates Thursday. 
    Thursday = 4, 
    // 
    // Summary: 
    //  Indicates Friday. 
    Friday = 5, 
    // 
    // Summary: 
    //  Indicates Saturday. 
    Saturday = 6, 
} 

Answer 4

我已经创建了这个C＃扩展方法，该方法基于备选的第一个工作日返回从零开始的索引。

DayOfWeek默认为星期日= 0，星期一= 1，...，星期六= 6，我们想要的（前）DayOfWeek是星期一= 0，周二= 1，...，星期日= 6

鉴于当前工作日是星期日：

DateTime.Now.DayOfWeek; // returns Sunday 
(int)DateTime.Now.DayOfWeek; // returns 0 
DateTime.Now.DayOfWeek(DayOfWeek.Monday); // returns 6  

public static class ExtensionMethods 
{ 
    /// <summary> 
    /// Returns an zero-based index where firstDayOfWeek = 0 and lastDayOfWeek = 6 
    /// </summary> 
    /// <param name="value"></param> 
    /// <param name="firstDayOfWeek"></param> 
    /// <returns>int between 0 and 6</returns> 
    public static int DayOfWeek(this DateTime value, DayOfWeek firstDayOfWeek) 
    { 
     var idx = 7 + (int)value.DayOfWeek - (int)firstDayOfWeek; 
     if (idx > 6) // week ends at 6, because Enum.DayOfWeek is zero-based 
     { 
      idx -= 7; 
     } 
     return idx; 
    } 
}