std:: common_type <std::chrono::duration>

From cppreference.com

< cpp ‎ | chrono ‎ | duration

Date and time utilities

Time point

time_point

(C++11)

clock_time_conversion

(C++20)

clock_cast

(C++20)

Duration

duration

(C++11)

Clocks

system_clock (C++11)
steady_clock (C++11)
is_clock (C++20)

utc_clock (C++20)
tai_clock (C++20)
high_resolution_clock (C++11)

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

Time of day

is_am is_pm

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

make12 make24

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

hh_mm_ss (C++20)

Calendar

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_spec last (C++20) (C++20)

Time zone

tzdb (C++20)
tzdb_list (C++20)
get_tzdb get_tzdb_list reload_tzdb remote_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

I/O

parse

(C++20)

C-style date and time

Defined in header `<chrono>`
template < class Rep1, class Period1, class Rep2, class Period2 > struct common_type < std:: chrono :: duration < Rep1, Period1 > , std:: chrono :: duration < Rep2, Period2 >> ;		(since C++11)

Exposes the type named type , which is the common type of two std::chrono::duration s, whose period is the greatest common divisor of Period1 and Period2 .

Member types

Member type	Definition
`type`	std:: chrono :: duration < typename std:: common_type < Rep1, Rep2 > :: type , /* see note */ >

Note

The period of the resulting duration can be computed by forming a ratio of the greatest common divisor of Period1 :: num and Period2 :: num and the least common multiple of Period1 :: den and Period2 :: den .

Example

Run this code

#include <chrono>
#include <iostream>
#include <type_traits>
 
// std::chrono already finds the greatest common divisor,
// likely using std::common_type<>. We make the type
// deduction externally. 
 
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';
}

Output:

30ms - 1100us = 28900us

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Execution support library (C++26)
Technical specifications
Symbols index
External libraries

std::common_type <std::chrono::time_point> (C++11)	specializes the std::common_type trait (class template specialization)
common_type (C++11)	determines the common type of a group of types (class template)

std:: common_type <std::chrono::duration>

Member types

Note

Example

See also

Navigation