echo_client.cpp

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

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

        boost::asio::ip::tcp::socket s{io_context};

        const boost::asio::ip::tcp::endpoint ep{
            boost::asio::ip::address::from_string("127.0.0.1"), 666};

        s.connect(ep);

        static constexpr size_t max_length = 100;

        std::cout << "Enter message: ";

        std::string request;

        std::getline(std::cin, request);

        boost::asio::write(
            s, boost::asio::buffer(request.data(), request.size() + 1));

        std::array<char, max_length> reply;
        size_t reply_length = s.read_some(boost::asio::buffer(reply));

        std::cout << "Reply is: ";
        std::cout.write(reply.data(), reply_length);
        std::cout << "\n";
    }
    catch (const boost::system::error_code & ec)
    {
        std::cerr << ec.message() << std::endl;
    }
    catch (std::exception & e)
    {
        std::cerr << e.what() << std::endl;
    }
}