代碼如下:

using System; 
namespace Utilities 
{ 
/// <summary> 
/// Common DateTime Methods. 
/// </summary> 
/// 
public enum Quarter 
{ 
First = 1, 
Second = 2, 
Third = 3, 
Fourth = 4 
} 
public enum Month 
{ 
January = 1, 
February = 2, 
March = 3, 
April = 4, 
May = 5, 
June = 6, 
July = 7, 
August = 8, 
September = 9, 
October = 10, 
November = 11, 
December = 12 
} 
public class DateUtilities 
{ 
#region Quarter 
public static DateTime GetStartOfQuarter( int Year, Quarter Qtr ) 
{ 
if( Qtr == Quarter.First ) // 1st Quarter = January 1 to March 31 
return new DateTime( Year, 1, 1, 0, 0, 0, 0 ); 
else if( Qtr == Quarter.Second ) // 2nd Quarter = April 1 to June 30 
return new DateTime( Year, 4, 1, 0, 0, 0, 0 ); 
else if( Qtr == Quarter.Third ) // 3rd Quarter = July 1 to September 30 
return new DateTime( Year, 7, 1, 0, 0, 0, 0 ); 
else // 4th Quarter = October 1 to December 31 
return new DateTime( Year, 10, 1, 0, 0, 0, 0 ); 
} 
public static DateTime GetEndOfQuarter( int Year, Quarter Qtr ) 
{ 
if( Qtr == Quarter.First ) // 1st Quarter = January 1 to March 31 
return new DateTime( Year, 3, DateTime.DaysInMonth( Year, 3 ), 23, 59, 59, 999 ); 
else if( Qtr == Quarter.Second ) // 2nd Quarter = April 1 to June 30 
return new DateTime( Year, 6, DateTime.DaysInMonth( Year, 6 ), 23, 59, 59, 999 ); 
else if( Qtr == Quarter.Third ) // 3rd Quarter = July 1 to September 30 
return new DateTime( Year, 9, DateTime.DaysInMonth( Year, 9 ), 23, 59, 59, 999 ); 
else // 4th Quarter = October 1 to December 31 
return new DateTime( Year, 12, DateTime.DaysInMonth( Year, 12 ), 23, 59, 59, 999 ); 
} 
public static Quarter GetQuarter( Month month ) 
{ 
if( month <= Month.March ) // 1st Quarter = January 1 to March 31 
return Quarter.First; 
else if( ( month >= Month.April ) && ( month <= Month.June ) ) // 2nd Quarter = April 1 to June 30 
return Quarter.Second; 
else if( ( month >= Month.July ) && ( month <= Month.September ) ) // 3rd Quarter = July 1 to September 30 
return Quarter.Third; 
else // 4th Quarter = October 1 to December 31 
return Quarter.Fourth; 
} 
public static DateTime GetEndOfLastQuarter() 
{ 
if( DateTime.Now.Month <= (int)Month.March ) //go to last quarter of previous year 
return GetEndOfQuarter( DateTime.Now.Year - 1, GetQuarter( Month.December )); 
else //return last quarter of current year 
return GetEndOfQuarter( DateTime.Now.Year, GetQuarter( (Month)DateTime.Now.Month)); 
} 
public static DateTime GetStartOfLastQuarter() 
{ 
if( DateTime.Now.Month <= 3 ) //go to last quarter of previous year 
return GetStartOfQuarter( DateTime.Now.Year - 1, GetQuarter( Month.December )); 
else //return last quarter of current year 
return GetStartOfQuarter( DateTime.Now.Year, GetQuarter( (Month)DateTime.Now.Month)); 
} 
public static DateTime GetStartOfCurrentQuarter() 
{ 
return GetStartOfQuarter( DateTime.Now.Year, GetQuarter( (Month)DateTime.Now.Month )); 
} 
public static DateTime GetEndOfCurrentQuarter() 
{ 
return GetEndOfQuarter( DateTime.Now.Year, GetQuarter( (Month)DateTime.Now.Month )); 
} 
#endregion 
#region Weeks 
public static DateTime GetStartOfLastWeek() 
{ 
int DaysToSubtract = (int)DateTime.Now.DayOfWeek + 7; 
DateTime dt = DateTime.Now.Subtract( System.TimeSpan.FromDays( DaysToSubtract ) ); 
return new DateTime( dt.Year, dt.Month, dt.Day, 0, 0, 0, 0 ); 
} 
public static DateTime GetEndOfLastWeek() 
{ 
DateTime dt = GetStartOfLastWeek().AddDays(6); 
return new DateTime( dt.Year, dt.Month, dt.Day, 23, 59, 59, 999 ); 
} 
public static DateTime GetStartOfCurrentWeek() 
{ 
int DaysToSubtract = (int)DateTime.Now.DayOfWeek ; 
DateTime dt = DateTime.Now.Subtract( System.TimeSpan.FromDays( DaysToSubtract ) ); 
return new DateTime( dt.Year, dt.Month, dt.Day, 0, 0, 0, 0 ); 
} 
public static DateTime GetEndOfCurrentWeek() 
{ 
DateTime dt = GetStartOfCurrentWeek().AddDays(6); 
return new DateTime( dt.Year, dt.Month, dt.Day, 23, 59, 59, 999 ); 
} 
#endregion 
#region Months 
public static DateTime GetStartOfMonth( int Month, int Year ) 
{ 
return new DateTime( Year, Month, 1, 0, 0, 0, 0 ); 
} 
public static DateTime GetEndOfMonth( int Month, int Year ) 
{ 
return new DateTime( Year, Month, DateTime.DaysInMonth( Year, Month ), 23, 59, 59, 999 ); 
} 
public static DateTime GetStartOfLastMonth() 
{ 
if( DateTime.Now.Month == 1 ) 
return GetStartOfMonth( 12, DateTime.Now.Year - 1); 
else 
return GetStartOfMonth( DateTime.Now.Month -1, DateTime.Now.Year ); 
} 
public static DateTime GetEndOfLastMonth() 
{ 
if( DateTime.Now.Month == 1 ) 
return GetEndOfMonth( 12, DateTime.Now.Year - 1); 
else 
return GetEndOfMonth( DateTime.Now.Month -1, DateTime.Now.Year ); 
} 
public static DateTime GetStartOfCurrentMonth() 
{ 
return GetStartOfMonth( DateTime.Now.Month, DateTime.Now.Year ); 
} 
public static DateTime GetEndOfCurrentMonth() 
{ 
return GetEndOfMonth( DateTime.Now.Month, DateTime.Now.Year ); 
} 
#endregion 
#region Years 
public static DateTime GetStartOfYear( int Year ) 
{ 
return new DateTime( Year, 1, 1, 0, 0, 0, 0 ); 
} 
public static DateTime GetEndOfYear( int Year ) 
{ 
return new DateTime( Year, 12, DateTime.DaysInMonth( Year, 12 ), 23, 59, 59, 999 ); 
} 
public static DateTime GetStartOfLastYear() 
{ 
return GetStartOfYear( DateTime.Now.Year - 1 ); 
} 
public static DateTime GetEndOfLastYear() 
{ 
return GetEndOfYear( DateTime.Now.Year - 1 ); 
} 
public static DateTime GetStartOfCurrentYear() 
{ 
return GetStartOfYear( DateTime.Now.Year ); 
} 
public static DateTime GetEndOfCurrentYear() 
{ 
return GetEndOfYear( DateTime.Now.Year ); 
} 
#endregion 
#region Days 
public static DateTime GetStartOfDay( DateTime date ) 
{ 
return new DateTime( date.Year, date.Month, date.Day, 0, 0, 0, 0 ); 
} 
public static DateTime GetEndOfDay( DateTime date ) 
{ 
return new DateTime( date.Year, date.Month, date.Day, 23, 59, 59, 999 ); 
} 
#endregion 
} 
}