#include <iostream>

#include <boost/bind.hpp>
#include <boost/ref.hpp>
#include <boost/asio.hpp>

void handler(
    boost::asio::signal_set &sset,
    const boost::system::error_code& error,
    int signal_number)
{
    if (!error)
    {
        sset.async_wait(
            boost::bind(
                 handler
                ,boost::ref(sset)
                ,boost::asio::placeholders::error
                ,boost::asio::placeholders::signal_number
            )
        );
        static bool first = true;
        if(first){
            std::cout << " A signal(SIGINT) occurred." << std::endl;
            // do something like writing data to a file
            first = false;
        }else{
            std::cout << " A signal(SIGINT) occurred, exiting...." << std::endl;
            exit(0);
        }
    }
}

int main(){
    // Construct a signal set registered for process termination.
    boost::asio::io_service io;
    boost::asio::signal_set signals(io, SIGINT);
    // Start an asynchronous wait for one of the signals to occur.
    signals.async_wait(
        boost::bind(
             handler
            ,boost::ref(signals)
            ,boost::asio::placeholders::error
            ,boost::asio::placeholders::signal_number
        )
    );

    io.run();
    size_t i;
    for(i=0;i<std::numeric_limits<size_t>::max();++i){
        // time stepping loop, do some computations
    }
    std::cout << i << std::endl;
    return 0;
}