std::chrono::floor(std::chrono::time_point)

 

C++

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Technical Specifications

 

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Date and time utilities

duration (C++11) time_point (C++11) time_of_day (C++20)	clock_time_conversion (C++20) clock_cast (C++20)
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C-style date and time

 

std::chrono::time_point

Member functions

time_point::time_point

time_point::time_since_epoch

time_point::operator+time_point::operator-

time_point::operator++time_point::operator-- (C++20)(C++20)

time_point::min

time_point::max

Non-member functions

operator+operator-

operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

time_point_cast

floor (C++17)

ceil (C++17)

round (C++17)

Helper classes

common_type

 

Defined in header <chrono>
template <class ToDuration, class Clock, class Duration> constexpr time_point<Clock, ToDuration> floor(const 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 an specialization of std::chrono::duration.

Parameters

tp

-

time point to round down

Return value

d rounded down to a the next time point using duration of type ToDuration.

Possible implementation

template <class T> struct is_duration : std::false_type {}; template <class Rep, class Period> struct is_duration< std::chrono::duration<Rep, Period>> : std::true_type {};   template <class To, class Clock, class FromDuration, class = std::enable_if_t<is_duration<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())}; }

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