How do I construct an ISO 8601 datetime in C++?

Question

I\'m working with the Azure REST API and they are using this to create the request body for table storage:

DateTime.UtcNow.ToString(\"o\")

Answer 1

If the time to the nearest second is precise enough, you can use strftime:

#include 
#include 

int main() {
    time_t now;
    time(&now);
    char buf[sizeof "2011-10-08T07:07:09Z"];
    strftime(buf, sizeof buf, "%FT%TZ", gmtime(&now));
    // this will work too, if your compiler doesn't support %F or %T:
    //strftime(buf, sizeof buf, "%Y-%m-%dT%H:%M:%SZ", gmtime(&now));
    std::cout << buf << "\n";
}

If you need more precision, you can use Boost:

#include 
#include 

int main() {
    using namespace boost::posix_time;
    ptime t = microsec_clock::universal_time();
    std::cout << to_iso_extended_string(t) << "Z\n";
}