print std::chrono::duration

cpp_time_ostream.log

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10 hours
36000 seconds
60000 intervals of 0.600000 (3/5) seconds each

print_duration_auto.cpp

#include <iostream>
#include <chrono>
#include <string>

namespace utility
{
    namespace chrono
    {
        constexpr inline const char* units( std::chrono::nanoseconds ) noexcept { return "nanoseconds" ; }
        constexpr inline const char* units( std::chrono::microseconds )  noexcept { return "microseconds" ; }
        constexpr inline const char* units( std::chrono::milliseconds )  noexcept { return "milliseconds" ; }
        constexpr inline const char* units( std::chrono::seconds )  noexcept { return "seconds" ; }
        constexpr inline const char* units( std::chrono::minutes )  noexcept { return "minutes" ; }
        constexpr inline const char* units( std::chrono::hours )  noexcept { return "hours" ; }

        template < std::intmax_t A, std::intmax_t B > struct gcd
        { static constexpr std::intmax_t value = gcd<B,A%B>::value ; };

        template < std::intmax_t A > struct gcd<A,0>
        { static constexpr std::intmax_t value = A ; };

        template < typename R, std::intmax_t N, std::intmax_t D >
        std::string units( std::chrono::duration< R, std::ratio<N,D> > )
        {
            constexpr auto NN = N / gcd<N,D>::value ;
            constexpr auto DD = D / gcd<N,D>::value ;
            return "intervals of " + std::to_string( double(N) / D ) +
                   " (" + std::to_string(NN) + '/' + std::to_string(DD) + ") seconds each" ;
        }
    }
}

template < typename R, std::intmax_t N, std::intmax_t D >
std::ostream& operator<< ( std::ostream& stm, std::chrono::duration< R, std::ratio<N,D> > d )
{ return stm << d.count() << ' ' << utility::chrono::units( decltype(d){} ) ; }

int main()
{
    std::chrono::hours duration_hrs(10) ;
    std::cout << duration_hrs << '\n'
              << std::chrono::duration_cast<std::chrono::seconds>(duration_hrs) << '\n'
              << std::chrono::duration< double, std::ratio<36,60> >(duration_hrs) << '\n' ;
}