c++求两个日期之间的间隔天数

#include <iostream>

using namespace std;

static const unsigned char MonthTable[12] = {
    31,28,31,30,31,30,31,31,30,31,30,31
};

class Date
{
public:
    Date(int year, int month, int day);
    Date operator -(const Date& date);
    //获取时间差
    int getDateDiff(const Date &d1 , const Date &d2);
    void dispDiff(void);
public:
    int year;
    int month;
    int day;
    //时间差
    int date_difference;
};

//获取相同年份的时间差
int getSameYearDays(const Date &d1, const Date &d2);
//获取相同月份的时间差
int getSameMonthDays(const Date &d1, const Date &d2);
//获取时间差
int getYearDays(const Date &d1, const Date &d2);
//是否为润年
bool isLeapYear(int year);
//比较时间大小
bool cmpDate(const Date &d1, const Date &d2);

Date::Date(int year = 2000, int month = 1, int day = 1)
{
    this->year = year;
    this->month = month;
    this->day = day;
    date_difference = 0;
}

int Date::getDateDiff(const Date &d1, const Date &d2)
{
    if(cmpDate(d1, d2))
        return getYearDays(d1, d2);
    else
        return getYearDays(d2, d1);
}

Date Date::operator -(const Date & date)
{
    Date d;
    d.date_difference = getDateDiff(*this, date);
    return d;
}

void Date::dispDiff()
{
    cout<<"days ="<< date_difference<<endl;
}

//比较时间大小
bool cmpDate(const Date &d1, const Date &d2)
{
    int flage = false;
    if(d1.year > d2.year)
    {
        flage = true;
    }
    else if(d1.year == d2.year)
    {
        if(d1.month > d2.month)
        {
            flage = true;
        }
        else if(d1.month == d2.month)
        {
            if(d1.day >= d2.day)
            {
                flage = true;
            }
            else
            {
                flage = false;
            }
        }
        else
        {
            flage = false;
        }
    }
    else
    {
        flage = false;
    }
    return flage;
}

bool isLeapYear(int year)
{
    return (year % 4 == 0 && year %100 != 0) || year % 400 == 0 ? true : false;
}

//获取相同月份的时间差
int getSameMonthDays(const Date &d1, const Date &d2)
{
    return d1.day - d2.day;
}

//获取相同年份的时间差
int getSameYearDays(const Date &d1, const Date &d2)
{
    int days = 0;
    //相同月份
    if(d1.month == d2.month)
    {
        //获取相同月份的时间差
        days = getSameMonthDays(d1, d2);
    }
    //不同月份
    else
    {
        //获取第一月份的时间差
        days = MonthTable[d2.month-1] - d2.day;
        //二月并且是润年天数+1
        if(d2.month == 2 && isLeapYear(d2.year))
        {
            days++;
        }
        //获取中间月份的时间差
        for(int i = d2.month + 1; i < d1.month; i++)
        {
            if(i == 2 && isLeapYear(d1.year))
            {
                days += 29;
            }
            else
            {
                days += MonthTable[i -1];
            }
        }
        //获取最后一月份的时间差
        days += d1.day;
    }
    return days;
}

int getYearDays(const Date &d1, const Date &d2)
{
    int days = 0;
    //相同年份
    if(d1.year == d2.year)
    {
        //获取相同年份的时间差
        days = getSameYearDays(d1,d2);
    }
    //不同年份
    else
    {
        //获取第一年的时间差
        days = getSameYearDays(Date(d2.year,12,31), d2);
        //获取中间年份的时间差
        for(int i = d2.year + 1; i < d1.year; i++)
        {
            days += 365;
            if(isLeapYear(i))
            {
                days++;
            }
        }
        //获取最后一年的时间差
        days += getSameYearDays(d1, Date(d1.year,1,1)) + 1;
    }
    return days;
}

int main()
{
    Date d1(2000,1,1),d2(2010,1,1);
    (d1 - d2).dispDiff();
    return 0;
}