5. Date类的实现

Date.h

class Date{// 友元声明(类的任意位置)friend ostream& operator<<(ostream& out, const Date& d);friend istream& operator>>(istream& in, Date& d);
public:// 获取某年某月的天数int GetMonthDay(int year, int month);// 全缺省的构造函数Date(int year = 1900, int month = 1, int day = 1);// 拷贝构造函数// d2(d1)// 形参加const，防止写反Date(const Date& d);// 析构函数~Date(){}// 打印void Print();// 赋值运算符重载// d2 = d3 -> d2.operator=(&d2, d3)Date& operator=(const Date& d);// 日期+=天数Date& operator+=(int day);// 日期+天数Date operator+(int day);// 日期-天数Date operator-(int day);// 日期-=天数Date& operator-=(int day);// 前置++Date& operator++();// 后置++Date operator++(int);// 后置--Date operator--(int);// 前置--Date& operator--();// >运算符重载bool operator>(const Date& d);// ==运算符重载bool operator==(const Date& d);// >=运算符重载bool operator >= (const Date& d);// <运算符重载bool operator < (const Date& d);// <=运算符重载bool operator <= (const Date& d);// !=运算符重载bool operator != (const Date& d);// 日期-日期 返回天数int operator-(const Date& d);private:int _year;int _month;int _day;};// cout << d1 => operator<<(cout, d1);
inline ostream& operator<<(ostream& out, const Date& d)
{out << d._year << "年" << d._month << "月" << d._day << "日" << endl;return out;
}// cin >> d1   operator(cin, d1);
inline istream& operator>>(istream& in, Date& d)
{in >> d._year >> d._month >> d._day;return in;
}

Date.cpp

// 获得某年某月某日
int Date::GetMonthDay(int year, int month)
{static int monthDayArray[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };if (month == 2 && ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))){return 29;}else{return monthDayArray[month];}
}// 全缺省构造函数
Date::Date(int year, int month, int day)
{_year = year;_month = month;_day = day;//检查日期是否合法if (!(year >= 1&& (month >= 1 && month <= 12)&& (day >= 1 && day <= GetMonthDay(year, month)))){cout << "非法日期" << endl;}
}// 拷贝构造函数
// 形参加const，防止写反
Date::Date(const Date & d)
{/*cout << "Data 拷贝构造" << endl;*/_year = d._year;_month = d._month;_day = d._day;}// 打印
void Date::Print()
{cout << _year << "/" << _month << "/" << _day << endl;
}// 赋值运算符重载// d2 = d3 -> d2.operator=(&d2, d3)Date& Date::operator=(const Date& d)
{if (this != &d){_year = d._year;_month = d._month;_day = d._day;}return *this;
}// 日期+=天数Date& Date::operator+=(int day)
{_day += day;while (_day > GetMonthDay(_year, _month)){_day -= GetMonthDay(_year, _month);_month++;if (_month == 13){++_year;_month = 1;}}return *this;
}// 日期+天数Date Date::operator+(int day)
{Date ret(*this);ret += day;return ret;
}// 日期-天数Date Date::operator-(int day)
{Date ret(*this);ret -= day;return ret;}// 日期-=天数Date& Date::operator-=(int day)
{if (day < 0){return *this += -day;}_day -= day;while (_day <= 0){--_month;if (_month == 0){--_year;_month = 12;}_day += GetMonthDay(_year, _month);}return *this;
}// 前置++
Date& Date::operator++()
{*this += 1;return *this;
}// 后置++ -- 多一个int参数主要是为了区分前置
// 构成函数重载
Date Date::operator++(int)
{Date tmp(*this);*this += 1;return tmp;
}// 后置--Date Date::operator--(int)
{Date tmp(*this);*this -= 1;return tmp;
}// 前置--Date& Date::operator--()
{*this -= 1;return *this;
}// >运算符重载
// d1>d2
bool Date::operator>(const Date& d)
{if (_year > d._year){return true;}else if (_year == d._year && _month > d._month){return true;}else if (_year == d._year && _month == d._month && _day > d._day){return true;}return false;
}// ==运算符重载
bool Date::operator==(const Date& d)
{return _year == d._year&& _month == d._month&& _day == d._day;
}// >=运算符重载
bool Date::operator>=(const Date& d)
{return *this > d || *this == d;
}// <=运算符重载
bool Date::operator<=(const Date& d)
{return !(*this > d);
}// <运算符重载
bool Date::operator<(const Date& d)
{return !(*this >= d);
}// !=运算符重载
bool Date::operator!=(const Date& d)
{return !(*this == d);
}// 日期-日期 返回天数
// d1-d2
int Date::operator-(const Date& d)
{Date max = *this;Date min = d;int flag = 1;if (*this < d){max = d;min = *this;flag = -1;}int n = 0;while (min != max){++n;++min;}return n * flag;
}