使用 boost asio 捕获 Ctrl-C

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; 
    }
}

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:

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.

增强 ASIO 的核心io_service对象，您请求的所有任务（尤其是异步任务）通常由io_service.

通过做：

// 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调用您的handler当它发生时。

问题是，你的io_service没有运行。

因此，如果您希望它正常工作，您需要启动它：

#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();
}

Then pressing Ctrl + C will do what you expect.

请注意，io_service基本上取代了无限循环，因此您在其中所做的任何事情都应该成为io_service.