指定した日付のカウントダウン(C++20必須)

#include <iostream>
#include <string>
#include <time.h>
#include <chrono>
#include <math.h>
#include <format>


void print_date(int target_year, int target_month, int target_day)
{
    auto cur_time = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
    struct tm Cur_Times;
    localtime_s(&Cur_Times, &cur_time);

    auto current_year = Cur_Times.tm_year + 1900;
    auto current_month = Cur_Times.tm_mon + 1;
    auto current_day = Cur_Times.tm_mday;

    auto diff_year = abs(current_year - target_year);
    auto diff_month = abs(current_month - target_month);
    auto diff_day = abs(current_day - target_day);

    std::cout << std::format("{0}年{1}月{2}日まであと", target_year, target_month, target_day);

    if (current_year != target_year) {
        std::cout << std::format("{0}年と", diff_year);
    }
    if (current_month != target_month) {
        std::cout << std::format("{0}か月と", diff_month);
    }
    if (diff_day != target_day) {
        std::cout << std::format("{0}日です。", diff_day);
    }
    std::cout << std::endl;
}

int main()
{
    print_date(2022, 2, 6);
    // "2022年2月6日まであと1か月と4日です。"
}