Defined in header <chrono> | ||
|---|---|---|
template <class ToDuration, class Clock, class Duration>
constexpr std::chrono::time_point<Clock, ToDuration>
floor(const std::chrono::time_point<Clock, Duration>& tp);
| (since C++17) |
Returns the largest time point t representable in ToDuration that is smaller or equal to tp.
The function does not participate in the overload resolution unless ToDuration is a specialization of std::chrono::duration.
| tp | - | time point to round down |
tp rounded down to the next time point using duration of type ToDuration.
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>
floor(const std::chrono::time_point<Clock, FromDuration>& tp)
{
return std::chrono::time_point<Clock, To>{
std::chrono::floor<To>(tp.time_since_epoch())};
} |
#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
|
(C++11) | converts a time point to another time point on the same clock, with a different duration (function template) |
|
(C++17) | converts a time_point to another, rounding up (function template) |
|
(C++17) | converts a time_point to another, rounding to nearest, ties to even (function template) |
|
(C++17) | converts a duration to another, rounding down (function template) |
|
(C++11)(C++11) | nearest integer not greater than the given value (function) |
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