date.h

C++参考书

#ifndef DATE_H
#define DATE_H
#include <iostream>
using namespace std ;

class Date
{
	public:
		Date( int m = 0, int d = 0, int y = 0 )
		{
			setDate( m, d, y ) ;
		}

		Date( const Date &d )
		{
			*this = d ;
		}

		~Date( void )
		{
			// nothing here ;
		}

		Date& operator = ( const Date &d )
		{
			ndays = d.ndays ;
			return *this ;
		}

	// ----------------------------------------------- overloaded operators
		Date operator + ( int n ) const
		{
			Date dt( *this ) ;
			dt += n ;
			return dt ;
		}

		Date operator - ( int n ) const
		{
			Date dt( *this ) ;
			dt -= n ;
			return dt ;
		}

		Date& operator += ( int n )
		{
			ndays += n ;
			return *this ;
		}

		Date& operator -= ( int n )
		{
			ndays -= n ;
			return * this ;
		}

		Date& operator ++ ( void )
		{
			++ndays ;
			return *this ;
		}

		Date operator ++ ( int )
		{
			Date dt( *this ) ;
			ndays++ ;
			return dt ;
		}

		Date& operator -- ( void )
		{
			--ndays ;
			return *this ;
		}

		Date operator -- ( int )
		{
			Date dt( *this ) ;
			ndays-- ;
			return dt ;
		}

		long operator - ( const Date &dt ) const
		{
			return ndays - dt.ndays ;
		}

		bool operator == ( const Date &dt ) const
		{
			return ndays == dt.ndays ;
		}

		bool operator != ( const Date &dt ) const
		{
			return ndays != dt.ndays ;
		}

		bool operator < ( const Date &dt ) const
		{
			return ndays < dt.ndays ;
		}

		bool operator > ( const Date &dt ) const
		{
			return ndays > dt.ndays ;
		}

		bool operator <= ( const Date &dt ) const
		{
			return ndays <= dt.ndays ;
		}

		bool operator >= ( const Date &dt ) const
		{
			return ndays >= dt.ndays ;
		}

	// ------------------------------------------------------ member functions
		void setDate( int, int, int ) ;

		void setMonth( int m )
		{
			*this = Date( m, getDay(), getYear() ) ;
		}

		void setDay( int d )
		{
			*this = Date( getMonth(), d, getYear() ) ;
		}

		void setYear( int y )
		{
			*this = Date( getMonth(), getDay(), y ) ;
		}

		void getDate( int &, int &, int & ) const ;
		int getMonth( void ) const ;
		int getDay( void ) const ;
		int getYear( void ) const ;

		virtual void display( void ) const ;

		bool isLeapYear( int y ) const
		{
			return ( ( y % 4 ) == 0 && ( y & 1000 ) != 0 ) ;
		}

		bool isLeapYear( void ) const
		{
			return isLeapYear( getYear() ) ;
		}
		
	protected:
		static const int dys[] ;
		long int ndays ;
} ;

const int Date::dys[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } ;

void Date::setDate( int m, int d, int y )
{
	if ( m < 1 || m > 12 || y < 1 ) {
		ndays = 0 ;
		return ;
	}

	ndays = ( y - 1 ) * 365 + ( y - 1 ) / 4 - ( y - 1 ) / 1000 ;

	for ( int i = 0; i < m; ++i ) {

		int dy = dys[i] ;

		if ( i == 1 && isLeapYear( y ) )
			dy++ ;

		if ( i < m - 1 )
			ndays += dy ;
		else if ( d > dy ) {
			ndays = 0 ;
			return ;
		}
	}
	ndays += d ;
}

void Date::getDate( int &mo, int &da, int &yr ) const
{
	da = ndays ;

	if  ( ndays == 0 ) {
		yr = mo = 0 ;
		return ;
	}

	for ( yr = 1; ; ++yr ) {
		int daysThisYear = isLeapYear( yr ) ? 366 : 365 ;

		if ( da <= daysThisYear )
			break ;

		da -= daysThisYear ;
	}

	for ( mo = 1; mo < 13; ++mo ) {
		int dy = dys[mo - 1] ;

		if ( mo == 2 && isLeapYear( yr ) )
			dy++ ;

		if ( da <= dy )
			break ;

		da -= dy ;
	}
}

int Date::getMonth( void ) const
{
	int mo, da, yr ;
	getDate( mo, da, yr ) ;

	return mo ;
}

int Date::getDay( void ) const
{
	int mo, da, yr ;
	getDate( mo, da, yr ) ;

	return da ;
}

int Date::getYear( void ) const
{
	int mo, da, yr ;
	getDate( mo, da, yr ) ;

	return yr ;
}

void Date::display( void ) const
{
	int mo, da, yr ;
	getDate( mo, da, yr ) ;

	cout << mo << '/' << da << '/' << yr << endl ;
}

inline Date operator + ( int n, const Date &dt )
{
	return dt + n ;
}

inline ostream& operator << ( ostream &os, const Date &dt )
{
	os << dt.getMonth() << '/' ;
	os << dt.getDay() << '/' ;
	os << dt.getYear() ;

	return os ;
}

inline istream& operator >> ( istream &is, Date &dt )
{
	int mo, da, yr ;
	is >> mo >> da >> yr ;
	dt.setDate( mo, da, yr ) ;

	return is ;
}

#endif