std::chrono:: ceil (std::chrono::duration)

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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 .

Parameters

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;
}

Example

Run this code 
#include <chrono>
#include <iostream>
 
int main()
{
    using namespace std::chrono_literals;
    using Min = std::chrono::minutes;
 
    std::cout
        << 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";
}

Output: 

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

See also

(C++11)
converts a duration to another, with a different tick interval
(function template)
(C++17)
converts a duration to another, rounding down
(function template)
(C++17)
converts a duration to another, rounding to nearest, ties to even
(function template)
(C++17)
converts a time_point to another, rounding up
(function template)
(C++11) (C++11)
nearest integer not less than the given value
(function)
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