How to get timestamp in microseconds in C++?

Question

I have tried this and other codes I found online but they did not work. My IDE is Xcode. Edit: When I tried the code on the link, the variable long long microseconds always returned 0. I would like to print the timestamp in this manner: (hour:minute:microseconds). For example, 15:17:09:134613464312.

Answer 1

Expanding on the previous answer here's what the OP was asking:

#include <iostream>
#include <chrono>
#include <ctime>

std::string ts() {
    using namespace std;
    using namespace std::chrono;
    using days = duration<int, ratio_multiply<hours::period, ratio<24> >::type>;
    high_resolution_clock::time_point now = high_resolution_clock::now();
    high_resolution_clock::duration tp = now.time_since_epoch();
    days d = duration_cast<days>(tp);
    tp -= d;
    hours h = duration_cast<hours>(tp);
    tp -= h;
    minutes m = duration_cast<minutes>(tp);
    tp -= m;
    seconds s = duration_cast<seconds>(tp);
    tp -= s;
    milliseconds ms = duration_cast<milliseconds>(tp);
    tp -= ms;
    microseconds us = duration_cast<microseconds>(tp);
    tp -= us;
    nanoseconds ns = duration_cast<nanoseconds>(tp);
    tp -= ns;
    
    std::ostringstream oss;
    oss << std::setfill('0')
        << std::setw(2) << h.count() << ":" 
        << std::setw(2) << m.count() << ":" 
        << std::setw(2) << s.count() << "." 
        << std::setw(3) << ms.count() 
        << std::setw(3) << us.count() 
        << std::setw(3) << ns.count();
    return oss.str();
}


void main ()
{
    std::cout << ts() << std::endl;
    std::cout << ts() << std::endl;
}
//output:
//22:43:00.295605757
//22:43:00.295640327

Answer 2

The method you use is correct.

If you the code between the two now() calls lasts less than a microseconds, microseconds will always be zero, since the number is not a floating point. If you have always zero, that means you need higher resolution (try nanoseconds).

Btw, if you simply want timestamp, you don't want to use this code since it is done to compute elapsed time between two time points. You can try something like this:

auto microseconds = std::chrono::duration_cast<std::chrono::microseconds>
    (std::chrono::high_resolution_clock::now().time_since_epoch()).count();

Which is really a timestamp and not a duration.

EDIT: To have the current microseconds count, you can do something like this:

#include <iostream>
#include <chrono>
#include <ctime>

using namespace std;
using namespace std::chrono;

using days = duration<int, ratio_multiply<hours::period, ratio<24> >::type>;

int main() {
    system_clock::time_point now = system_clock::now();
    system_clock::duration tp = now.time_since_epoch();
    days d = duration_cast<days>(tp);
    tp -= d;
    hours h = duration_cast<hours>(tp);
    tp -= h;
    minutes m = duration_cast<minutes>(tp);
    tp -= m;
    seconds s = duration_cast<seconds>(tp);
    tp -= s;
    cout << tp.count() << "\n";
    return 0;
}

This will print the current microseconds count.

Hours:Minutes:Seconds is pretty easy.