#include <iostream>
#include <ctime>
//
// ---------------------------------------------------------
// Function: daysUntilChristmas
// Purpose : Calculate how many days remain until Christmas.
// ---------------------------------------------------------
//
int daysUntilChristmas() {
// Get the current system time (in seconds since 1970)
time_t now = time(nullptr);
// Convert to a tm structure (broken-down local time)
tm* today = localtime(&now);
// Extract the current year (tm_year counts from 1900)
int year = today->tm_year + 1900;
// Build a tm structure for Christmas of the current year
tm christmas = {};
christmas.tm_year = year - 1900; // Year since 1900
christmas.tm_mon = 11; // December (0-based index)
christmas.tm_mday = 25; // 25th day of the month
// Convert Christmas date to time_t
time_t christmas_time = mktime(&christmas);
// If Christmas already passed this year, calculate for next year
if (difftime(christmas_time, now) < 0) {
christmas.tm_year += 1; // Move to next year
christmas_time = mktime(&christmas);
}
// Calculate difference in seconds between now and Christmas
double seconds = difftime(christmas_time, now);
// Convert seconds → days (60 sec * 60 min * 24 hr)
int days = static_cast<int>(seconds / (60 * 60 * 24));
return days;
}
int main() {
int days = daysUntilChristmas();
std::cout << "Days until Christmas: " << days << std::endl;
}
/*
run:
Days until Christmas: 210
*/
