使用boost asio捕获Ctrl-C [英] Using boost asio to Catch Ctrl-C

问题描述

我正在尝试在应用程序中捕获 Ctrl - C ，如以下MWE中所示

I'm trying to catch the Ctrl-C in application as demonstrated in the following MWE

#include <boost/asio/signal_set.hpp>
#include <iostream>

void handler( const boost::system::error_code& error , int signal_number )
{
    std::cout << "handling signal " << signal_number << std::endl;
}

int main( int argc , char** argv )
{
    boost::asio::io_service io_service;

    // Construct a signal set registered for process termination.
    boost::asio::signal_set signals(io_service, SIGINT );

    // Start an asynchronous wait for one of the signals to occur.
    signals.async_wait( handler );

    char choice;
    while( true )
    {
        std::cout << "Press a key: " << std::endl;
        std::cin >> choice; 
    }
}

不幸的是，当我按下 Ctrl + C 时，没有调用

handler().相反，循环不再等待用户输入，如下所示:

Unfortunately handler() is not called when I press Ctrl+C. On the contrary the loop no longer waits for user input as shown below:

c:\tmp>CtrlC.exe
Press a key:
d
Press a key:
e
Press a key:
Press a key:
Press a key:
Press a key:
Press a key:
Press a key:
Press a key:
Press a key:
Press a key:

如果重要的话，我在Windows上，我知道有Windows特定的捕获 Ctrl + C 的方法，但是我想使用boost为方便移植提供了可能.

If it matters, I'm on Windows and I know that there is a Windows specific way to catch Ctrl+C but I'd like to use boost if possible for ease of porting.

推荐答案

以ASIO为中心，以 io_service 对象为中心，您请求的所有任务(尤其是异步任务)通常由 io_service .

boost ASIO in centered on the io_service object, all the tasks you request (especially the async ones) are usually handled by the io_service.

这样做:

// Start an asynchronous wait for one of the signals to occur.
signals.async_wait( handler );

您需要服务异步等待信号，并在发生这种情况时调用您的 handler .

You require the service to wait on the signals asynchronously and call your handler when it happens.

问题是，您的 io_service 没有运行.

The thing is, your io_service is not running.

因此，如果您希望它正常工作，则需要启动它:

So if you want it to work correctly you need to start it:

#include <boost/asio/signal_set.hpp>
#include <iostream>

void handler( const boost::system::error_code& error , int signal_number )
{
  std::cout << "handling signal " << signal_number << std::endl;
  exit(1);
}

int main( int argc , char** argv )
{
  boost::asio::io_service io_service;

  // Construct a signal set registered for process termination.
  boost::asio::signal_set signals(io_service, SIGINT );

  // Start an asynchronous wait for one of the signals to occur.
  signals.async_wait( handler );

  io_service.run();
}

然后按 Ctrl + C 即可完成您的期望.

Then pressing Ctrl + C will do what you expect.

请注意， io_service 基本上会取代无限循环，因此您在其中执行的所有操作都应成为 io_service 的任务.

Note that the io_service basically replaces your infinite loop, so anything you would have done inside of it should become tasks for the io_service.

这篇关于使用boost asio捕获Ctrl-C的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！