std::chrono::time_point_cast
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template <class ToDuration, class Clock, class Duration> time_point<Clock, ToDuration> time_point_cast( const time_point<Clock, Duration> &t); |
(C++11以上) (C++14未満) |
|
template <class ToDuration, class Clock, class Duration> constexpr time_point<Clock, ToDuration> time_point_cast( const time_point<Clock, Duration> &t); |
(C++14以上) | |
std::chrono::time_point の時間単位を別の時間単位に変換します。
引数
| t | - | 変換する time_point
|
戻り値
std::chrono::time_point<Clock, ToDuration>(std::chrono::duration_cast<ToDuration>(t.time_since_epoch()))。
ノート
time_point_cast は、 ToDuration が duration のインスタンスである場合にのみ、オーバーロード解決に参加します。
例
Run this code
#include <iostream>
#include <chrono>
using Clock = std::chrono::high_resolution_clock;
using Ms = std::chrono::milliseconds;
using Sec = std::chrono::seconds;
template<class Duration>
using TimePoint = std::chrono::time_point<Clock, Duration>;
inline void print_ms(const TimePoint<Ms>& time_point)
{
std::cout << time_point.time_since_epoch().count() << " ms\n";
}
int main()
{
TimePoint<Sec> time_point_sec(Sec(4));
// implicit cast, no precision loss
TimePoint<Ms> time_point_ms(time_point_sec);
print_ms(time_point_ms); // 4000 ms
time_point_ms = TimePoint<Ms>(Ms(5756));
// explicit cast, need when precision loss may happens
// 5756 truncated to 5000
time_point_sec = std::chrono::time_point_cast<Sec>(time_point_ms);
print_ms(time_point_sec); // 5000 ms
}
出力:
4000 ms
5000 ms