NAME¶

std::chrono::ceil(std::chrono::time_point) - std::chrono::ceil(std::chrono::time_point)

Synopsis¶

Defined in header <chrono>
template <class ToDuration, class Clock, class Duration>

constexpr std::chrono::time_point<Clock, ToDuration> (since C++17)

ceil(const std::chrono::time_point<Clock, Duration>& tp);

Returns the smallest time point t representable in ToDuration that is greater or
equal to tp.

The function does not participate in the overload resolution unless ToDuration is a
specialization of std::chrono::duration.

Parameters¶

tp - time point to round up

Return value¶

tp rounded up to the next time point using duration of type ToDuration.

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>>>
constexpr std::chrono::time_point<Clock, To>
ceil(const std::chrono::time_point<Clock, FromDuration>& tp)
{
return std::chrono::time_point<Clock, To>{
std::chrono::ceil<To>(tp.time_since_epoch())};
}

Example¶

// Run this code

#include <iostream>
#include <chrono>
#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

See also¶

time_point_cast converts a time point to another time point on the
(C++11) same clock, with a different duration
(function template)
floor(std::chrono::time_point) converts a time_point to another, rounding down
(C++17) (function template)
round(std::chrono::time_point) converts a time_point to another, rounding to
(C++17) nearest, ties to even
(function template)
ceil(std::chrono::duration) converts a duration to another, rounding up
(C++17) (function template)
ceil
ceilf nearest integer not less than the given value
ceill (function)
(C++11)
(C++11)