floor.md

floor

• chrono[meta header]
• std::chrono[meta namespace]
• function[meta id-type]
• cpp17[meta cpp]

namespace std::chrono {
  template <class ToDuration, class Clock, class Duration>
  constexpr time_point<Clock, ToDuration>
    floor(const time_point<Clock, Duration>& tp);
}

概要

分解能が低いtime_pointに変換する際に、床関数 (負の無限大方向への丸め、切り下げ) による丸めを行う。

戻り値

return time_point<Clock, ToDuration>{floor<ToDuration>(tp.time_since_epoch())};

• floor[link /reference/chrono/duration/floor.md]
• tp.time_since_epoch()[link time_since_epoch.md]

例

#include <iostream>
#include <chrono>

using namespace std::chrono;

int main()
{
  using MTimePoint = time_point<system_clock, milliseconds>;
  using STimePoint = time_point<system_clock, seconds>;

  MTimePoint mp{milliseconds(1500)};
  STimePoint sp = floor<seconds>(mp);

  std::cout << sp.time_since_epoch().count() << std::endl;
}

• floor[color ff0000]
• milliseconds[link /reference/chrono/milliseconds.md]
• seconds[link /reference/chrono/seconds.md]
• system_clock[link /reference/chrono/system_clock.md]
• sp.time_since_epoch()[link time_since_epoch.md]
• count()[link /reference/chrono/duration/count.md]

出力

1

バージョン

言語

• C++17

処理系

• GCC, C++17 mode: 7.3
• Clang, C++17 mode: 3.8
• Visual C++: ??

関連項目

名前	説明
time_point_cast	ゼロ方向への丸め
ceil	正の無限大方向への丸め
round	偶数方向への丸め

参照

• P0092R1 Polishing <chrono>