CODEWITHSUNDEEP
c++timezone
bpeikes
bpeikes

Reputation: 3705

How convert time to specific timezone on windows in C++?

Have a Unix timestamp and I need equivalents of localtime_s, but where I can pass in the timezone. Alternately I'm looking for a way to change the timezone programatically for the app (not the whole system), so that localtime_s returns the correct values.

Strangely enough, if I set TZ environment variable in a shell to GMT, and then launch my application, localtime_s returns values in GMT.

I've tried:

::SetEnvironmentVariable("TZ", "GMT");
tzset();

But it does not change the results of later calls to localtime_s

Note that I'm running the application on Windows 7, using VS 2013.

Upvotes: 0

Views: 459

Answers (1)

Howard Hinnant
Howard Hinnant

Reputation: 219325

If you are willing to use a free, open-source 3rd party library, this works on VS-2013. There are many examples on how to use it here:

https://github.com/HowardHinnant/date/wiki/Examples-and-Recipes

For example here is how to output the current time in New York and Chicago:

#include "tz.h"
#include <iostream>

int
main()
{
    auto now = std::chrono::system_clock::now();
    std::cout << "Current time in New York: "
              << date::make_zoned("America/New_York", now) << '\n';
    std::cout << "Current time in Chicago : "
              << date::make_zoned("America/Chicago", now) << '\n';
}

This just output for me:

Current time in New York: 2016-08-12 10:36:24.670966 EDT
Current time in Chicago : 2016-08-12 09:36:24.670966 CDT

Upvotes: 1

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