关于运算符的重载,我在这里介绍到 += , -= , - ,+ ;
注意:
在这里,我们+= 与 + 的区别, -= 与 - 同样也是。
在用到 += 与 -= 的时候,它是有一个赋值的过程,等于是将原来的值进行了改变,而另外两种就只是在其重载函数中实现了这种运算,并没有改变原来的值。
#include<iostream>
using namespace std;
class Date
{
public:
Date(int year = 1900, int month = 1, int day = 1)
{
_year = year;
_month = month;
_day = day;
}
// 获取某年某月的天数
int GetMonthDay(int year, int month)
{
if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12)
{
return 31;
}
else if (month == 4 || month == 6 || month == 9 || month == 11)
{
return 30;
}
else
{
if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))
{
return 29;
}
else
return 28;
}
}
日期+=天数
Date& operator+=(int day)
{
if (day < 0)
{
return *this - (0 - day);
}
this->_day += day;
int daysOfMonth = 0;
while (this->_day >(daysOfMonth = this->GetMonthDay(this->_year, this->_month)))
{
this->_month += 1;
if (this->_month > 12)
{
this->_year += 1;
this->_month = 1;
}
this->_day -= daysOfMonth;
}
cout << this->_year << "-" << this->_month << "-" << this->_day << endl;
return *this;
}
// 日期+天数
Date operator+(int day)
{
if (day < 0)
{
return *this - (0 - day);
}
Date temp(*this);
temp._day += day;
int daysOfMonth = 0;
while (temp._day >(daysOfMonth = temp.GetMonthDay(temp._year, temp._month)))
{
temp._month += 1;
if (temp._month > 12)
{
temp._year += 1;
temp._month = 1;
}
temp._day -= daysOfMonth;
}
cout << temp._year << "-" << temp._month << "-" << temp._day << endl;
return temp;
}
// 日期-天数
Date operator-(int day)
{
if (day < 0)
{
return *this + (0 - day);
}
Date temp(*this);
temp._day -= day;
while (temp._day <= 0)
{
temp._month -= 1;
if (temp._month == 0)
{
temp._year -= 1;
temp._month = 12;
}
temp._day += temp.GetMonthDay(temp._year, temp._month);
}
cout << temp._year << "-" << temp._month << "-" << temp._day << endl;
return temp;
}
// 日期-=天数
Date& operator-=(int day)
{
if (day < 0)
{
return *this + (0 - day);
}
this->_day -= day;
while (this->_day <= 0)
{
this->_month -= 1;
if (this->_month <= 0)
{
this->_year -= 1;
this->_month = 12;
}
this->_day += this->GetMonthDay(this->_year, this->_month);
}
cout << this->_year << "-" << this->_month << "-" << this->_day << endl;
return *this;
}
private:
int _year;
int _month;
int _day;
};
int main()
{
Date d1(2020, 9, 20);
Date d2;
d1 += 100;
d1 -= 100;
d2 = d1 + 100;
d2 = d1 - 100;
return 0;
}