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

 

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std::chrono::duration

成员函数
duration::duration duration::operator= duration::count duration::zero duration::min duration::max duration::operator+duration::operator-	duration::operator++duration::operator-- duration::operator+=duration::operator-=duration::operator*=duration::operator/=duration::operator%=
非成员函数
operator+operator-operator*operator/operator% operator==operator!=operator<operator<=operator>operator>=operator<=> (C++20 前)(C++20) operator<< (C++20)	duration_cast floor (C++17) ceil (C++17) round (C++17) abs (C++17) operator""h (C++14) operator""min (C++14) operator""s (C++14) operator""ms (C++14) operator""us (C++14) operator""ns (C++14) from_stream (C++20)
辅助类
common_type treat_as_floating_point      duration_values	formatter<std::chrono::duration> (C++20) hash<std::chrono::duration> (C++26)

 

在标头 <chrono> 定义
template <class ToDuration, class Rep, class Period> constexpr ToDuration ceil(const std::chrono::duration<Rep, Period>& d);		(C++17 起)

返回可表示为 ToDuration 的大于或等于 d 的最小时长 t 。

函数不参与重载决议，除非 ToDuration 是 std::chrono::duration 的特化。

参数

d

-

要转换的时长

返回值

向上取整到 ToDuration 类型时长的 d 。

可能的实现

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; }

示例

运行此代码

#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";
}

输出：

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

参阅

duration_cast (C++11)	转换时长到另一个拥有不同嘀嗒间隔的时长 (函数模板)
floor(std::chrono::duration) (C++17)	以向下取整的方式，将一个时长转换为另一个时长 (函数模板)
round(std::chrono::duration) (C++17)	转换时长到另一个时长，就近取整，偶数优先 (函数模板)
ceil(std::chrono::time_point) (C++17)	转换 time_point 到另一个，向上取整 (函数模板)
ceilceilfceill (C++11)(C++11)	不小于给定值的最接近整数值 (函数)