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

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< cpp‎ | chrono‎ | duration

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 <iostream>
    #include <chrono>

    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

duration_cast (C++11) | converts a duration to another, with a different tick interval (function template)
floor(std::chrono::duration) (C++17) | converts a duration to another, rounding down (function template)
round(std::chrono::duration) (C++17) | converts a duration to another, rounding to nearest, ties to even (function template)
ceil(std::chrono::time_point) (C++17) | converts a time_point to another, rounding up (function template)
ceil ceilf ceill (C++11)(C++11) | nearest integer not less than the given value (function)

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