如何更改哪一天是一週中的第一天？

Question

我需要在asp.net中更改一週的第一天，即我希望星期六成爲本週的第一天。

例如，下面的代碼應該在星期一返回3：

(int)DateTime.Now.DayOfWeek 

Answer 1

我想你只需要你的使用（DayOfWeek Enumeration）改變文化。

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

Answer 2

使用以下代碼更改asp.net應用程序中的第一個星期幾。

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

不能影響的DateTime.DayOfWeek的值，因爲這是一種類型的System.DayOfWeek這是枚舉（即，的值是恆定的）。 System.DayOfWeek的定義在下面的代碼塊中。因此，如果您想在週一和週六將DayOfWeek視爲3這一週的第一天，那麼我必須假設您需要基於1到7的編號系統。在這種情況下，您可以使用((int)DateTime.Now.DayOfWeek+1) % 7 + 1來獲得您想要的號碼。如果你不需要這個計算，最好只將DateTime.Now.DayOfWeek的值與它的枚舉常量（例如if(DateTime.Now.DayOfWeek == DayOfWeek.Monday) ...）進行比較。

// 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

我已經創建了這個C＃擴展方法，該方法基於備選的第一個工作日返回從零開始的索引。

DayOfWeek默認爲星期日= 0，星期一= 1，...，星期六= 6，我們想要的（前）DayOfWeek是星期一= 0，週二= 1，...，星期日= 6

鑑於當前工作日是星期日：

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; 
    } 
}