std::chrono::round(std::chrono::duration)

Since C++17

Header: <chrono>

Returns the value t representable in ToDuration that is the closest to d. If there are two such values, returns the even value (that is, the value t such that t % 2 == 0).

# Declarations

template< class ToDuration, class Rep, class Period >
constexpr ToDuration round( const std::chrono::duration<Rep, Period>& d );

(since C++17)

# Parameters

d: duration to convert

# Return value

d rounded to the nearest duration of type ToDuration, rounding to even in halfway cases.

# Example

#include <chrono>
#include <iomanip>
#include <iostream>
 
int main()
{
    using namespace std::chrono_literals;
    std::cout << "Duration\tFloor\tRound\tCeil\n";
    for (using Sec = std::chrono::seconds;
        auto const d : {+4999ms, +5000ms, +5001ms, +5499ms, +5500ms, +5999ms,
                        -4999ms, -5000ms, -5001ms, -5499ms, -5500ms, -5999ms})
        std::cout << std::showpos << d << "\t\t"
                  << std::chrono::floor<Sec>(d) << '\t'
                  << std::chrono::round<Sec>(d) << '\t'
                  << std::chrono::ceil <Sec>(d) << '\n';
}