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

int CTimeRyan::GetLocalTimeZoneByC()
{
	time_t time_utc;  
	struct tm tm_local;  

	// Get the UTC time  
	time(&time_utc);  

	// Get the local time  
	// Use localtime_r for threads safe for linux 
	//localtime_r(&time_utc, &tm_local);
	localtime_s(&tm_local, &time_utc);

	time_t time_local;  
	struct tm tm_gmt;  

	// Change tm to time_t   
	time_local = mktime(&tm_local);  

	// Change it to GMT tm
	//gmtime_r(&time_utc, &tm_gmt);//linux
	gmtime_s(&tm_gmt, &time_utc);  

	int time_zone = tm_local.tm_hour - tm_gmt.tm_hour;  
	if (time_zone < -12) {  
		time_zone += 24;   
	} else if (time_zone > 12) {  
		time_zone -= 24;  
	}  

	return time_zone;
}