std::chrono::round(std::chrono::time_point)
From cppreference.com
< cpp | chrono | time point
Defined in header <chrono>
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template< class ToDuration, class Clock, class Duration > constexpr std::chrono::time_point<Clock, ToDuration> |
(since C++17) | |
Returns the nearest time point to tp representable in ToDuration
, rounding to even in halfway cases.
The function does not participate in the overload resolution unless ToDuration
is a specialization of std::chrono::duration and std::chrono::treat_as_floating_point_v<typename ToDuration::rep> is false.
Contents |
[edit] Parameters
tp | - | time point to round to nearest |
[edit] Return value
tp rounded to nearest time point using duration of type ToDuration
, rounding to even in halfway cases.
[edit] Possible implementation
namespace detail { template<class> inline constexpr bool is_duration_v = false; template<class Rep, class Period> inline constexpr bool is_duration_v< std::chrono::duration<Rep, Period>> = true; } template<class To, class Clock, class FromDuration, class = std::enable_if_t<detail::is_duration_v<To> && !std::chrono::treat_as_floating_point_v<typename To::rep>>> constexpr std::chrono::time_point<Clock, To> round( const std::chrono::time_point<Clock, FromDuration>& tp) { return std::chrono::time_point<Clock, To>{ std::chrono::round<To>(tp.time_since_epoch())}; } |
[edit] Example
Run this code
#include <chrono> #include <iostream> #include <string> template<typename TimePoint> std::string to_string(const TimePoint& time_point) { return std::to_string(time_point.time_since_epoch().count()); } int main() { using namespace std::literals::chrono_literals; using Sec = std::chrono::seconds; std::cout << "Time point\t" "Cast\t" "Floor\t" "Round\t" "Ceil\n"; std::cout << "(ms)\t\t" "(s)\t" "(s)\t" "(s)\t" "(s)\n"; for (const auto value_ms : {5432ms, 5678ms}) { std::chrono::time_point<std::chrono::system_clock, std::chrono::milliseconds> time_point_ms(value_ms); std::cout << to_string(time_point_ms) << "\t\t" << to_string(std::chrono::time_point_cast<Sec>(time_point_ms)) << '\t' << to_string(std::chrono::floor<Sec>(time_point_ms)) << '\t' << to_string(std::chrono::round<Sec>(time_point_ms)) << '\t' << to_string(std::chrono::ceil<Sec>(time_point_ms)) << '\n'; } }
Output:
Time point Cast Floor Round Ceil (ms) (s) (s) (s) (s) 5432 5 5 5 6 5678 5 5 6 6
[edit] See also
(C++11) |
converts a time point to another time point on the same clock, with a different duration (function template) |
converts a time_point to another, rounding up (function template) | |
converts a time_point to another, rounding down (function template) | |
(C++17) |
converts a duration to another, rounding to nearest, ties to even (function template) |
(C++11)(C++11)(C++11)(C++11)(C++11)(C++11)(C++11)(C++11)(C++11) |
nearest integer, rounding away from zero in halfway cases (function) |