查找周，使用當前日期？在C＃中？

Question

在C＃中，我如何查找當前日期的星期，我正在嘗試獲取當前日期的星期編號，您能否幫助我，謝謝。

Answer 1

見Calendar.GetWeekOfYear

using System; 
using System.Globalization; 

public class Example 
{ 
    public static void Main() 
    { 
     DateTimeFormatInfo dfi = DateTimeFormatInfo.CurrentInfo; 
     DateTime date1 = new DateTime(2011, 1, 1); 
     Calendar cal = dfi.Calendar; 

     Console.WriteLine("{0:d}: Week {1} ({2})", date1, 
         cal.GetWeekOfYear(date1, dfi.CalendarWeekRule, 
              dfi.FirstDayOfWeek), 
         cal.ToString().Substring(cal.ToString().LastIndexOf(".") + 1));  
    } 
} 
// The example displays the following output: 
//  1/1/2011: Week 1 (GregorianCalendar) 

Answer 2

如果您需要本週的「全球」號碼，您可以使用此：

using System; 
using System.Globalization;  

DateTime date = DateTime.Now; 
int res = 0; 

// First day of year 
res = CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(date, CalendarWeekRule.FirstDay, DateTimeFormatInfo.CurrentInfo.FirstDayOfWeek); 

// (Default) First four day week from Sunday 
res = CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(date, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Sunday); 

// First four day week from StartOfWeek 
res = CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(date, CalendarWeekRule.FirstFourDayWeek, DateTimeFormatInfo.CurrentInfo.FirstDayOfWeek); 

// First full week from Sunday 
res = CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(date, CalendarWeekRule.FirstFullWeek, DayOfWeek.Sunday); 

// First full week from StartOfWeek 
res = CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(date, CalendarWeekRule.FirstFullWeek, DateTimeFormatInfo.CurrentInfo.FirstDayOfWeek); 

如果您需要在一個月星期數，使用不便像這樣的代碼：

DateTime beginningOfMonth = DateTime.Now; 

while (date.Date.AddDays(1).DayOfWeek != CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek) 
    date = date.AddDays(1); 

int result = (int)Math.Truncate((double)date.Subtract(beginningOfMonth).TotalDays/7f) + 1;