CODEWITHSUNDEEP
c++timec++-chrono
doctopus
doctopus

Reputation: 5647

How to get hh:mm:ss.uuuuuu timestamp in c++?

I'm looking to print hh:mm:ss.uuuuuu timestamps in C++. It seems like I need to use the chrono library and std::chrono::use high_resolution_clock::now()?

I'm unsure how to proceed from here however.

Upvotes: 1

Views: 701

Answers (1)

Howard Hinnant
Howard Hinnant

Reputation: 218700

This is easily accomplished with this C++20 chrono preview library which works with C++11/14/17:

#include "date/date.h"
#include <chrono>
#include <iostream>

int
main()
{
    using namespace date;
    using namespace std;
    using namespace std::chrono;
    cout << format("%T", floor<microseconds>(system_clock::now())) << '\n';
}

Just output for me:

19:31:54.033196

This will port to C++20 by:

  • Drop #include "date/date.h"
  • Drop using namespace date;
  • Change "%T" to "{:%T}"

This is a header-only, open-source library.

The output is UTC. If you need local time, that is available too, but the library is not header-only. It is at the same link and would be used like this:

#include "date/tz.h"
#include <chrono>
#include <iostream>

int
main()
{
    using namespace date;
    using namespace std;
    using namespace std::chrono;
    zoned_time zt{current_zone(), floor<microseconds>(system_clock::now()))};
    cout << format("%T", zt) << '\n';
}

The above syntax uses C++17. If you're using C++11 or 14 change zoned_time to zoned_time<microseconds>.

Some installation is required for the tz.h library.

Upvotes: 2

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