Date类

class Date
{
public:
    Date();
    Date(int y,int m,int d);
    Date(const Date& dt);
    Date& add_year(int n);
    Date& add_month(int n);
    Date& add_day(int n);
    bool leapyear(int n);
    Date operator+(int n);
    Date operator-(int n);
    Date& operator++();
    Date& operator--();
    Date& operator+=(int n);
    Date& operator-=(int n);
    bool operator==(Date dt) const;
    bool operator!=(Date dt) const;
    bool operator<(Date dt) const;
    bool operator>(Date dt) const;
    int operator-(Date dt);
    int get_week();
    static void set_today(int y,int m,int d);
    void print();

private:
    int y,m,d;
    week w;
    static Date default_date;
};

#include"date.h"
#include<iostream>

using namespace std;

#define CASE break;case
typedef enum wk{sun=0,mon,tue,wed,thu,fri,sat}week;

const int month[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};

Date Date::default_date=Date(2008,3,16);
void Date::set_today(int y,int m,int d)
{
    default_date.y=y;
    default_date.m=m;
    default_date.d=d;
}

Date::Date()
{
    *this=default_date;
}

Date::Date(int y,int m,int d)
{
    this->y=y;
    this->m=m;
    this->d=d;
}

Date::Date(const Date &dt)
{
    y=dt.y;
    m=dt.m;
    d=dt.d;
}

Date& Date::add_day(int n)
{
    d+=n;
    int day=m==2&&leapyear(y)?month[m]+1:month[m];
    while(d>day)
    {
        m++;
        d-=day;
        day=m==2&&leapyear(y)?month[m]+1:month[m];
    }
    if(m>12)
    {
        y+=m/12;
        m=m%12;
    }
    return *this;
}

Date& Date::add_month(int n)
{
    m+=n;
    if(m>12)
    {
        y+=m/12;
        m=m%12;
    }
    int day=m==2&&leapyear(y)?month[m]+1:month[m];
    if(d>day)
    {
        m++;
        d-=day;
    }
    return *this;
}

Date& Date::add_year(int n)
{
    if(leapyear(y)&&!leapyear(y+n)&&m==2&&d==29)
    {
        m=3;
        d=1;
    }
    y+=n;
    return *this;
}

bool Date::operator==(Date dt) const
{
    if(y==dt.y&&m==dt.y&&d==dt.d)
        return 1;
    return 0;
}
bool Date::operator !=(Date dt) const
{
    if(*this==dt)
        return 0;
    return 1;
}

bool Date::operator<(Date dt) const
{
    if(y!=dt.y)
        return y<dt.y;
    if(m!=dt.m)
        return m<dt.m;
    return d<dt.d;
}

bool Date::operator>(Date dt) const
{
    if(y!=dt.y)
        return y>dt.y;
    if(m!=dt.m)
        return m>dt.m;
    return d>dt.d;
}

Date Date::operator+(int n)
{
    this->add_day(n);
    return *this;
}

Date Date::operator-(int n)
{
    while(n)
    {
        int day=(m-1)==2&&leapyear(y)?month[m-1?m-1:12]+1:month[m-1?m-1:12];
        if(n>day)
        {
            d-=day;
            n-=day;
            m--;
        }
        else
        {
            if(n>=d)
            {
                d=day+d-n;
                m--;
            }
            else
                d-=n;

        }
        if(m<0)
        {
            m=12;
            y--;
        }
    }
    return *this;
}

int Date::operator -(Date dt)
{
    int sum=0,day;
    while(y>dt.y+1)
    {
        sum+=leapyear(dt.y)?366:365;
        dt.y++;
    }
    if(y>dt.y&&(m>dt.m||m==dt.m&&d>=dt.d))
    {
        sum+=leapyear(dt.y)?366:365;
        dt.y++;
    }
    while(m>dt.m)
    {
        day=dt.m==2&&leapyear(dt.y)?month[dt.m]+1:month[dt.m];
        sum+=day;
        dt.m++;
    }
    sum+=d-dt.d;
    return sum;

}

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

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

Date& Date::operator++()
{
    *this+=1;
    return *this;
}

Date& Date::operator--()
{
    *this-=1;
    return *this;
}

bool Date::leapyear(int n)
{
    if(n%4)
        return 0;
    if(n%100==0)
        if(n%400)
            return 0;
    return 1;
}

void Date::print()
{
    cout<<y<<"."<<m<<"."<<d<<"\t";
    w=(week)(get_week()%7);
    switch(w)
    {
    case 0:
        cout<<"sunday";
    CASE(1):
        cout<<"monday";
    CASE(2):
        cout<<"tuesday";
    CASE(3):
        cout<<"wednesday";
    CASE(4):
        cout<<"thursday";
    CASE(5):
        cout<<"friday";
    CASE(6):
        cout<<"saturday";
        break;
    default:
        cout<<"the week is wrong";
    }
    cout<<endl;
}

int Date::get_week()
{
    return *this>default_date?(*this-default_date)%7:7-(default_date-*this)%7;
}