学步园

　　发一个专门处理时间和日期的类库，记录以备查询。

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
    }
}