Defined in header <chrono>
template <class ToDuration, class Rep, class Period>
constexpr ToDuration ceil(const std::chrono::duration<Rep, Period>& d);
(since C++17)

Returns the smallest duration t representable in ToDuration that is greater or equal to d.

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


d - duration to convert

Return value

d rounded up to a 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 Rep, class Period,
          class = std::enable_if_t<detail::is_duration_v<To>>>
constexpr To ceil(const std::chrono::duration<Rep, Period>& d)
    To t = std::chrono::duration_cast<To>(d);
    if (t < d)
        return t + To{1};
    return t;


#include <iostream>
#include <chrono>
int main()
    using namespace std::chrono_literals;
    using Min = std::chrono::minutes;
        << std::showpos
        << "ceil(+2.4min) = " << std::chrono::ceil<Min>(+2.4min).count() << "min\n"
        << "ceil(-2.4min) = " << std::chrono::ceil<Min>(-2.4min).count() << "min\n"
        << "ceil(+0.0min) = " << std::chrono::ceil<Min>(+0.0min).count() << "min\n";


ceil(+2.4min) = +3min
ceil(-2.4min) = -2min
ceil(+0.0min) = +0min

See also

converts a duration to another, with a different tick interval
(function template)
converts a duration to another, rounding down
(function template)
converts a duration to another, rounding to nearest, ties to even
(function template)
converts a time_point to another, rounding up
(function template)
nearest integer not less than the given value

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.