std::chrono::time_point_cast
STD::时间::时间[医]点[医]铸造
template | | (since C++11) (until C++14) |
---|---|---|
template <class ToDuration, class Clock, class Duration> constexpr time_point<Clock, ToDuration> time_point_cast( const time_point<Clock, Duration> &t | | (since C++14) |
转换std::chrono::time_point
从一段时间到另一段时间。
参数
t | - | time_point to convert from |
---|
返回值
std::chrono::time_point<Clock, ToDuration>(std::chrono::duration_cast<ToDuration>(t.time_since_epoch()))...
注记
time_point_cast
将只参与重载解决方案。ToDuration
的实例化duration
...
例
二次
#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
}
二次
产出:
二次
4000 ms
5000 ms
二次
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