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C++ , return string from function; boost::asio read / write


C++ , return string from function; boost::asio read / write

By : user2956167
Date : November 22 2020, 10:54 AM
it fixes the issue I get a compile error, additionally I cannot boost::asio::read buf without giving it array elements. ,
The most generic way would be use a asio::streambuf
code :
streambuf sb;
size_t transferred = read (port, sb, ec);
std::string buf;
buf.resize(transferred);
sb.sgetn(&buf[0], buf.size());
std::string buf(100u, '\0');
size_t transferred = read (port, buffer(buf), ec);
buf.resize(transferred);
streambuf sb;
size_t transferred = read_until(port, sb, "\r\n", ec);


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boost::asio::write does not seem to work while boost::asio::read is outstanding

boost::asio::write does not seem to work while boost::asio::read is outstanding


By : s1conan
Date : March 29 2020, 07:55 AM
This might help you Asio socket is not thread-safe, so you may not access it from different threads. Use async_read and async_write instead.
error: no type named 'const_iterator' in 'class boost::asio::mutable_buffer' when trying to read using boost::asio::asyn

error: no type named 'const_iterator' in 'class boost::asio::mutable_buffer' when trying to read using boost::asio::asyn


By : C Sunil Reddy
Date : March 29 2020, 07:55 AM
it should still fix some issue The buffer parameter given to the async_read() free function needs to meet the MutableBuffer sequence requirements. You should use mutable_buffers_1 instead of mutable_buffer.
code :
void Connection::asyncReceiveHeader()
{
    Buffer* header = new Buffer(packetHeaderSize);
    ba::mutable_buffers_1 buffer = ba::buffer(header->pointer(), header->size());
    auto readHandler = bind(&Connection::headerReceived, this, ba::placeholders::error, ba::placeholders::bytes_transferred, header);

    ba::async_read(socket, buffer, readHandler);
}
boost::asio::read prevents boost:asio::write from sending data to Java Socket

boost::asio::read prevents boost:asio::write from sending data to Java Socket


By : collin
Date : March 29 2020, 07:55 AM
help you fix your problem It seems that the code itself works fine. I have tried it outside the surrounding software - so it somehow has to be a problem within that software.
boost::asio::read throws compilation error 'read_some' is not a member of 'boost::shared_ptr<boost::asio::ip::tcp::so

boost::asio::read throws compilation error 'read_some' is not a member of 'boost::shared_ptr<boost::asio::ip::tcp::so


By : user2856203
Date : March 29 2020, 07:55 AM
Hope that helps I am trying to build up a client to get data via a specific protocol from a server. I know that my code is not the best - but at the moment I am still experimenting with the basic functions of Boost ASIO. , Okey, I've just found the problem.
code :
// creating socket
  boost::shared_ptr<boost::asio::ip::tcp::socket>   socket(new boost::asio::ip::tcp::socket(*io_service));
  boost::asio::async_read(*socket, boost::asio::buffer(receiveCommandHeader.buffer, receiveCommandHeader.length),
    boost::asio::transfer_all(), boost::bind(HandleRead, ec));
Write directly to cout using boost's boost::asio::read

Write directly to cout using boost's boost::asio::read


By : ph60
Date : March 29 2020, 07:55 AM
To fix the issue you can do Directly, as in zero-copy? Only if the OS supports it.
On some POSIX compliant OS-es you might be able to use the sendfile syscall to actually zero-copy the stream iff the output is being redirected to an actual file.
code :
#include <boost/asio.hpp>
#include <iostream>
using boost::asio::ip::tcp;

int main() {
    tcp::iostream socket(tcp::endpoint {{}, 6767});
    std::cout << socket.rdbuf() << std::flush;
}
#include <boost/asio.hpp>
#include <iostream>
using boost::asio::ip::tcp;

int main() {
    boost::asio::io_service svc;
    tcp::socket s(svc);
    s.connect(tcp::endpoint {{}, 6767});

    tcp::iostream stream;
    stream.rdbuf()->assign(tcp::v4(), s.native_handle());

    std::cout << stream.rdbuf() << std::flush;
}
#include <boost/asio.hpp>
#include <boost/iostreams/copy.hpp>
#include <iostream>
using boost::asio::ip::tcp;

int main() {
    tcp::iostream socket(tcp::endpoint {{}, 6767});
    boost::iostreams::copy(socket, std::cout);
}
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