int datediff(Date d1, Date d2) {
int diff = 0;
if (d2.yyyy != d1.yyyy) {
diff += (d2.yyyy - d1.yyyy) * DAYS_IN_YEAR;
int ystart;
int yend;
if (d2.yyyy > d1.yyyy) {
ystart = d1.yyyy;
yend = d2.yyyy;
} else {
ystart = d2.yyyy;
yend = d1.yyyy;
}
for (; ystart < yend; ystart++) {
if (isleap(ystart)) {
diff++;
}
}
}
int day2 = daysinyear(d2);
int day1 = daysinyear(d1);
return day2 - day1 + diff;
}
/**
* Convert the given time in seconds elapsed since the beginning of the given
* year. It is assumed that year <= t[0]
*/
long long int secondsfrom(int year, const int* val)
{
long long int res = 0;
if (val[5] != -1) res += val[5];
if (val[4] != -1) res += val[4] * 60;
if (val[3] != -1) res += val[3] * 3600;
if (val[2] != -1) res += (val[2]-1) * 3600 * 24;
if (val[1] != -1)
for (int i = 1; i < val[1]; ++i)
res += daysinmonth(val[0], i) * 3600 * 24;
for (int i = year; i < val[0]; ++i)
res += daysinyear(i) * 3600 * 24;
return res;
}