c++ - 将 uint64_t 转换为 time_point

Question

我有一个 uint64_t 值，它表示自纪元以来的纳秒数。现在我需要将其转换为 time_point。

目前我有这段代码:

std::chrono::time_point<std::chrono::nanoseconds> uptime(std::chrono::nanoseconds(deviceUptime));

稍后我想打印类似 Fri Feb 10 15:13:04 2017 的内容。为此，我想使用这段代码:

std::time_t t = std::chrono::system_clock::to_time_t(uptime);
std::cout << "Device time: " << std::ctime(&t) << std::endl;

但是我得到一个错误:

No viable conversion from 'time_point<std::chrono::nanoseconds>' to 'const time_point<std::__1::chrono::system_clock>'

我需要做什么才能将 time_point 转换为 ctime 可以使用的格式？还是有更好的方法来解决这个问题？

Answer 1

试试这个:

uint64_t uptime = 0;
using time_point = std::chrono::system_clock::time_point;
time_point uptime_timepoint{std::chrono::duration_cast<time_point::duration>(std::chrono::nanoseconds(uptime))};
std::time_t t = std::chrono::system_clock::to_time_t(uptime_timepoint);

或者:

std::time_t t = uptime / 1000000000;