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如何在 c++ 中每天的某个时间调用一个函数？

发布于 2024-10-07 18:04:18 字数 127 浏览 0 评论 0原文

好吧，我需要弄清楚如果我的应用程序正在运行，如何在某个时间调用函数。

它可能会在一个 while 循环中检查时间，但我不希望它每分钟检查一次时间，但我不希望它错过确切的时间，比如 18:00。

有什么办法吗？

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裂开嘴轻声笑有多痛 2024-10-14 18:04:18

如果您想从已运行的程序中调用特定函数，请使用 Boost 的日期时间库和Asio。

#include <boost/date_time/gregorian/gregorian_types.hpp>
#include <boost/date_time/posix_time/posix_time_types.hpp>
#include <boost/asio.hpp>

namespace gregorian = boost::gregorian;
namespace posix_time = boost::posix_time;
namespace asio = boost::asio;

asio::io_service io_service_;
asio::deadline_timer timer_ (io_service_);

然后设定时间。这是使用所需时间字符串的示例，例如“18:00:00”。（请注意，Boost 默认使用 UTC 作为时间戳！）

gregorian::date today = gregorian::day_clock::local_day();
posix_time::time_duration usertime = posix_time::duration_from_string(time)
posix_time::ptime expirationtime (today, usertime);

现在设置计时器来调用 foo()：

timer_.expires_at (expirationtime);
timer_.async_wait (foo);    // use Boost::bind() if you want a member function

您可以使用以下命令向 timer_ 添加任意数量的计时器：上面两个代码片段。当一切准备就绪时：

io_service_.run ();

请注意，这将接管当前线程。因此，如果您希望程序的其余部分继续运行，则必须从不同的线程调用 run()。（显然，请使用 Boost 的 Thread 库。）

If you want to call a specific function from within a program that's already running, use Boost's Date Time library and Asio.

#include <boost/date_time/gregorian/gregorian_types.hpp>
#include <boost/date_time/posix_time/posix_time_types.hpp>
#include <boost/asio.hpp>

namespace gregorian = boost::gregorian;
namespace posix_time = boost::posix_time;
namespace asio = boost::asio;

asio::io_service io_service_;
asio::deadline_timer timer_ (io_service_);

Then set the time. This is an example using a string of the desired time, like "18:00:00". (Note that Boost defaults to UTC for the timestamps!)

gregorian::date today = gregorian::day_clock::local_day();
posix_time::time_duration usertime = posix_time::duration_from_string(time)
posix_time::ptime expirationtime (today, usertime);

Now set the timer to call foo():

timer_.expires_at (expirationtime);
timer_.async_wait (foo);    // use Boost::bind() if you want a member function

You can add as many timers as you want to timer_ by using the above two code snippets. When everything is ready:

io_service_.run ();

Note that this will take over the current thread. So you must call run() from a different thread if you want the rest of your program to keep going. (Obviously, use Boost's Thread library for that.)

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