C++ Advent Calendar 2013 9日目の記事のサンプルコードです。 http://d.hatena.ne.jp/fjnl/ C++ Advent Calendar: http://partake.in/events/91328710-3c7b-436e-bd4e-4d98d88333f9

client.cpp

#include <iostream>
#include <thread>
#include <future>
#include <string>
#include <vector>
#include <algorithm>
#include <boost/asio.hpp>
#include <boost/exception/all.hpp>

namespace asio = boost::asio;
using boost::asio::ip::tcp;

void client_main(asio::io_service& io_service) {
    tcp::resolver resolver(io_service);
    tcp::resolver::query q("localhost", "1234");
    tcp::socket socket(io_service);

    asio::connect(socket, resolver.resolve(q));

    asio::streambuf buf;
    std::string input;

    while (std::cin) {
        buf.consume(buf.size());

        std::cout << ">> " << std::flush;

        std::getline(std::cin, input);
        input += "\n";

        asio::write(socket, asio::buffer(input));

        asio::read_until(socket, buf, "\n");

        std::istream stream(&buf);
        stream >> input;
        std::cout << "--> " << input << std::endl;
    }
}

int main() {
    try {
        asio::io_service io_service;
        auto thread = std::async([&] { io_service.run(); });

        client_main(io_service);
        thread.get();
    } catch (...) {
        std::cerr << "error: " << boost::current_exception_diagnostic_information() << std::endl;
        return 1;
    }

    return 0;
}

server.cpp

#include <iostream>
#include <thread>
#include <future>
#include <string>
#include <vector>
#include <algorithm>
#include <boost/asio.hpp>
#include <boost/asio/spawn.hpp>
#include <boost/exception/all.hpp>
#include <boost/lexical_cast.hpp>

namespace asio = boost::asio;
using boost::asio::ip::tcp;

#ifndef NDEBUG
#  define DEBUG(expr) do { std::cout << expr << std::endl; } while (0)
#else
#  define DEBUG(expr) do {} while (0)
#endif

void connection_rountine(asio::yield_context yield, tcp::socket s) {
    int acc = 0;
    boost::system::error_code ec;
    asio::streambuf buf;
    std::string str;

    DEBUG("enter connection_rountine");

    for (;;) {
        buf.consume(buf.size());

        auto const n = asio::async_read_until(s, buf, "\n", yield[ec]);
        if (ec) break;

        std::istream stream(&buf);
        int value;
        stream >> value;

        DEBUG("read " << n << " byte: " << value);

        acc += value;
        str = std::to_string(acc) + "\n";

        asio::async_write(s, asio::buffer(str), yield[ec]);
        if (ec) break;
    }

    DEBUG("leave connection_rountine");
}

void server_main(asio::io_service& io_service) {
    asio::spawn(io_service, [&] (asio::yield_context yield) {
        tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), 1234));
        boost::system::error_code ec;

        for (;;) {
            DEBUG("accept");

            tcp::socket socket(io_service);

            acceptor.async_accept(socket, yield);

            asio::spawn(io_service,
                        [&] (asio::yield_context yc) { connection_rountine(yc, std::move(socket)); });
        }
    });
}

int main() {
    try {
        asio::io_service io_service;

        server_main(io_service);

        io_service.run();
    } catch (...) {
        std::cerr << "error: " << boost::current_exception_diagnostic_information() << std::endl;
        return 1;
    }

    return 0;
}