std::common_type(std::chrono::duration)

(C++11)

(C++20)

(C++11)

system_clock (C++11)
steady_clock (C++11)
high_resolution_clock (C++11)

is_clock (C++20)
utc_clock (C++20)
tai_clock (C++20)

gps_clock (C++20)
file_clock (C++20)
local_t (C++20)

is_amis_pm

(C++20)(C++20)

make12make24

(C++20)(C++20)

hh_mm_ss (C++20)

day (C++20)
month (C++20)
year (C++20)
weekday (C++20)
operator/ (C++20)
year_month_day (C++20)

year_month_day_last (C++20)
year_month_weekday (C++20)
year_month_weekday_last (C++20)
weekday_indexed (C++20)
weekday_last (C++20)
month_day (C++20)

month_day_last (C++20)
month_weekday (C++20)
month_weekday_last (C++20)
year_month (C++20)
last_speclast (C++20)(C++20)

tzdb (C++20)
tzdb_list (C++20)
get_tzdbget_tzdb_listreload_tzdbremote_version (C++20)(C++20)(C++20)(C++20)
sys_info (C++20)

local_info (C++20)
nonexistent_local_time (C++20)
ambiguous_local_time (C++20)
locate_zone (C++20)
current_zone (C++20)
time_zone (C++20)
choose (C++20)

zoned_traits (C++20)
zoned_time (C++20)
time_zone_link (C++20)
leap_second (C++20)
leap_second_info (C++20)
get_leap_second_info (C++20)

/ chrono

parse

(C++20)

C

[edit]

`<chrono>`
`template <class Rep1, class Period1, class Rep2, class Period2> struct common_type<std::chrono::duration<Rep1, Period1>, std::chrono::duration<Rep2, Period2>> { typedef std::chrono::duration< typename std::common_type<Rep1, Rep2>::type, /* */> type; };`		( C++11)

type, std::chrono::duration, Period1 Period2.

, Period1::num Period2::num Period1::den Period2::den.

#include <type_traits>
#include <iostream>
#include <chrono>

// std::chrono     ,
// ,  std::common_type<>.  
//  .

template <typename T,typename S>
constexpr auto durationDiff(const T& t, const S& s)
    -> typename std::common_type<T,S>::type
{
    typedef typename std::common_type<T,S>::type Common;
    return Common(t) - Common(s);
}


int main() 
{
    using namespace std::literals;

    constexpr auto ms = 30ms;
    constexpr auto us = 1100us;
    constexpr auto diff = durationDiff(ms, us);

    std::cout << ms << " - " << us << " = " << diff << '\n';
}

:

30ms - 1100us = 28900us

std::common_type<std::chrono::time_point> (C++11)	std::common_type ( ) []
common_type (C++11)	( ) []

cppreference.com

std::common_type(std::chrono::duration)