C++ 计算当前时区偏移量秒数（GMT/UNIX偏移量）

通过BOOST

#include <boost/date_time/posix_time/posix_time.hpp>

#include <boost/date_time/local_time/local_time.hpp>

                boost::posix_time::ptime localTime = boost::posix_time::second_clock::local_time();
                boost::posix_time::time_duration gmtOffset = localTime - boost::posix_time::second_clock::universal_time();
                return gmtOffset.total_seconds();

通过C标准库

#include <stdio.h>
#include <time.h>

#ifdef _WIN32
#include <Windows.h>

#define localtime_r(t, res) localtime_s(res, t)
#define gmtime_r(t, res) gmtime_s(res, t)
#endif

int get_utc_offset() {
                time_t t = time(NULL);

                struct tm local_tm;
                struct tm gmt_tm;

                localtime_r(&t, &local_tm);
                gmtime_r(&t, &gmt_tm);

                struct tm* local = &local_tm;
                struct tm* gmt = &gmt_tm;

                int hour_diff = local->tm_hour - gmt->tm_hour;
                int min_diff  = local->tm_min - gmt->tm_min;

                if (local->tm_yday > gmt->tm_yday) 
                {
                    hour_diff += 24;
                }
                else if (local->tm_yday < gmt->tm_yday) 
                {
                    hour_diff -= 24;
                }
            
                return hour_diff * 3600 + min_diff * 60;
}