如何将`std :: chrono :: milliseconds`转换为`boost :: posix_time :: milliseconds` [英] How to cast `std::chrono::milliseconds` to `boost::posix_time::milliseconds`

问题描述

我正在使用boost :: asio :: deadline_timer，以便在 tcp套接字上的async_read操作之前设置一些超时.我正在使用 boost 1.61 .

I am using a boost::asio::deadline_timer like so to set some timeout before an async_read operation on a tcp socket. I am using boost 1.61.

long time_out_millis = 2000;
boost::asio::deadline_timer theTimer(theSocket.get_io_service(), boost::posix_time::milliseconds(time_out_millis));

问题:
我代码的其他部分使用std::chrono::milliseconds.我想使用std::chrono而不是"long time_out_millis"&如果可能，请使用std::chrono::milliseconds而不是boost::posix_time::milliseconds.我该怎么办?

Problem:
Other parts of my code use std::chrono::milliseconds. I want use std::chrono instead of the "long time_out_millis" & if possible use std::chrono::milliseconds instead of boost::posix_time::milliseconds. How can I do that?

问题:
那么，如何在这里使用std::chrono::milliseconds呢?我可以从std::chrono::milliseconds投射到boost::posix_time::milliseconds吗?

Question:
So, how can I use std::chrono::milliseconds here ? Is there a way I cast from std::chrono::milliseconds to boost::posix_time::milliseconds ?

推荐答案

直接解决方案:duration_cast<>:

using namespace std::chrono;
using namespace std::chrono_literals; 

boost::posix_time::seconds(duration_cast<milliseconds>(2s).count());

还是不好.但这是你的钥匙.

Still not nice. But this is your key.

在任何c ++ 11或更高版本的场景中，

In any c++11 or higher scenario, simply

#include <boost/asio/high_resolution_timer.hpp>

从下到上享受完全在std::chrono上参数化的计时器.不再有阻抗不匹配的情况:

And enjoy a timer completely parameterized on std::chrono from bottom to top. No more impedance mismatch:

在Coliru上直播

#include <boost/asio/high_resolution_timer.hpp>
using namespace std::chrono_literals;

int main() {
    boost::asio::io_service svc;

    boost::asio::high_resolution_timer tim(svc);

    tim.expires_from_now(1s);
    tim.expires_from_now(100ms);
    tim.expires_from_now(3h);
    tim.expires_from_now(15'000us);
    tim.expires_from_now(15'000'000ns);
}

请注意，这会更改您的

long time_out_millis = 2000;

变成类似

Clock::duration timeout = 2000ms;

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