C++ 日期差值

思路是令小的日期天数不断++，一直追赶到与大的日期相等。其中要注意润年！

#include <iostream>
using namespace std;
bool is_leapyear(int _year) {
    if ((_year % 4 == 0 && _year % 100 != 0) || _year % 400 == 0)
        return 1;
    else
        return 0;
}

int main() {



    int month[13][2] = {{0, 0}, {31, 31}, {28, 29}, {31, 31}, {30, 30}, {31, 31}, {30, 30}, {31, 31}, {31, 31}, {30, 30}, {31, 31}, {30, 30}, {31, 31}};

    int year1, month1, day1, time1;
    int year2, month2, day2, time2;
    while (cin >> time1 >> time2) {


        if (time1 < time2) {
            int a = time1;
            time1 = time2;
            time2 = a;
        }
        int ant = 1;
        year1 = time1 / 10000;
        month1 = time1 % 10000 / 100;
        day1 = time1 % 10000 % 100;
        year2 = time2 / 10000;
        month2 = time2 % 10000 / 100;
        day2 = time2 % 10000 % 100;
        while (year1 > year2 || month1 > month2 || day1 > day2) {
            day2++;
            ant++;
            if (day2 == month[month2][is_leapyear(year2)]+1) {
                day2 = 1;
                month2++;
            }
            if (month2 == 13) {
                year2++;
                month2 = 1;
            }
        
        }
        cout << ant;
    }
}