QUdpSocket transmission

[Slavius]

I try to run QT example "Broadcast Sender Example". (http://doc.qt.io/qt-5/qtnetwork-broa...r-example.html).
It run without errors, but datagrams are not sended. And I have messages "QNativeSocketEngine::writeDatagram() was called not in QAbstractSocket::BoundState or QAbstractSocket::ConnectedState" in Application Output tab. Can anybode help me?

sender.h

#ifndef SENDER_H
#define SENDER_H

#include <QWidget>

QT_BEGIN_NAMESPACE
class QDialogButtonBox;
class QLabel;
class QPushButton;
class QTimer;
class QUdpSocket;
QT_END_NAMESPACE

class Sender : public QWidget
{
Q_OBJECT

public:
Sender(QWidget *parent = 0);

private slots:
void startBroadcasting();
void broadcastDatagram();

private:
QLabel *statusLabel;
QPushButton *startButton;
QPushButton *quitButton;
QDialogButtonBox *buttonBox;
QUdpSocket *udpSocket;
QTimer *timer;
int messageNo;
};

#endif

---

main.cpp

#include <QApplication>

#include "sender.h"

int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Sender sender;
sender.show();
return app.exec();
}

---

sender.cpp

#include <QtWidgets>
#include <QtNetwork>

#include "sender.h"

Sender::Sender(QWidget *parent)
: QWidget(parent)
{
statusLabel = new QLabel(tr("Ready to broadcast datagrams on port 45454"));
statusLabel->setWordWrap(true);

startButton = new QPushButton(tr("&Start"));
quitButton = new QPushButton(tr("&Quit"));

buttonBox = new QDialogButtonBox;
buttonBox->addButton(startButton, QDialogButtonBox::ActionRole);
buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);

timer = new QTimer(this);
//! [0]
udpSocket = new QUdpSocket(this);
//! [0]
messageNo = 1;

connect(startButton, SIGNAL(clicked()), this, SLOT(startBroadcasting()));
connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
connect(timer, SIGNAL(timeout()), this, SLOT(broadcastDatagram()));

QVBoxLayout *mainLayout = new QVBoxLayout;
mainLayout->addWidget(statusLabel);
mainLayout->addWidget(buttonBox);
setLayout(mainLayout);

setWindowTitle(tr("Broadcast Sender"));
}

void Sender::startBroadcasting()
{
startButton->setEnabled(false);
timer->start(1000);
}

void Sender::broadcastDatagram()
{
statusLabel->setText(tr("Now broadcasting datagram %1").arg(messageNo));
//! [1]
QByteArray datagram = "Broadcast message " + QByteArray::number(messageNo);
udpSocket->writeDatagram(datagram.data(), datagram.size(),
QHostAddress::Broadcast, 45454);
//! [1]
++messageNo;
}

[m.sue]

Hi @Slavius

On some machines you will have to allow trafic in the firewall.

-Michael.