QUdpSocket issue

ODБOï

Hi,
I have a simple udp socket server. It recives what hosts write on, but it can't answer them. i get QIODevice::write (QUdpSocket): device not open when i try to call write(). Can please someone tell me what is missing ?

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);

    QUdpSocket *udpSrv = new QUdpSocket();
    udpSrv->bind(QHostAddress::LocalHost, 1234);

    QObject::connect(udpSrv,&QUdpSocket:: bytesWritten,[&](){
        qDebug()<<"Server answered !"; //
    });

    QObject::connect(udpSrv, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error),[&]() {
        qDebug()<< "Error : " << udpSrv->errorString();
    });

    QObject::connect(udpSrv,&QUdpSocket::readyRead,[&](){
        QByteArray buffer;
        QHostAddress sender;
        quint16 senderPort;
        buffer.resize(static_cast<int>(udpSrv->pendingDatagramSize()));

        udpSrv->readDatagram(buffer.data(), buffer.size(),
                             &sender, &senderPort);

        QString req = QString::fromStdString(buffer.toStdString());

        qDebug()<<"client : " << req;

        if(req=="Hi"){
            udpSrv->write("Hello!"); // QIODevice::write (QUdpSocket): device not open
        }
        else{
            udpSrv->write("Say Hello First !"); // QIODevice::write (QUdpSocket): device not open
        }
    });

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

raven-worx

@LeLev
you should rather use QUdpSocket::writeDatagram()
but first before anything else you should read the docs and/or at least one of the official examples...

ODБOï

@raven-worx said in QUdpSocket issue:

should

my bad
thank you

ODБOï

@raven-worx
now i'm able to write to the socket, but the tool i use as client (Packet Sender) does not receive anything, do you have an idea why ?

            QString resp = "Hello client !";
            qint64 nwritten = udpSrv->writeDatagram(resp.toLatin1(),resp.length(),QHostAddress::LocalHost,1234);
            qDebug()<< "wrote : " << nwritten; // output 14

edit

i fixed, last parameter must be senderPort instead of 1234
writeDatagram(resp.toLatin1(),resp.length(),QHostAddress::LocalHost,senderPort)

Cabrera1M

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