Getting current time of a different timezone using C++
New answer for a very old question.
Given a C++11 or C++14 compiler, and this timezone library, the current time in Singapore is:
#include "tz.h"
#include <iostream>
int
main()
{
using namespace std::chrono;
std::cout << date::make_zoned("Asia/Singapore", system_clock::now()) << '\n';
}
which just output for me:
2015-08-19 05:25:05.453824 SGT
This gives the current local date, time and abbreviation in use. And it is based off of the <chrono>
library and the IANA timezone database.
std::chrono::system_clock::now()
returns a time stamp in the UTC timezone. This program locates the timezone information for "Asia/Singapore", and translates the UTC timestamp into a pair representing the local time and the current timezone for that location.
The above program is independent of the computer's current timezone.
C++20 Update
In C++20 you can now do this (once your vendor ships it):
#include <chrono>
#include <iostream>
int
main()
{
using namespace std::chrono;
std::cout << zoned_time{"Asia/Singapore", system_clock::now()} << '\n';
}
Output:
2015-08-19 05:25:05.453824 SGT
One implementation would be to use time
to get the current time in UTC and then manipulate the TZ
environment variable to your destination timezone. Then use localtime_r
to convert to that timezone's local time.