Time for action – sending a text via UDP

As an example, let's assume that we have two sockets of the QUpSocket type. We will call the first one socketA and the other socketB. Both are bound to the localhost, socketA to the 52000 port and socketB to the 52001 port. So, if we want to send the string "Hello!" from socketA to socketB, we have to write in the application that is holding socketA:

socketA->writeDatagram(QByteArray("Hello!"), QHostAddress("127.0.0.1"), 52001);

Here, we have used the convenient function of writeDatagram(), which takes QByteArray instead of const char* and qint64. The class that holds socketB must have the socket's readyRead() signal connected to a slot. This slot will then be called because of our writeDatagram() call, assuming that the datagram is not lost! In the slots, we read the datagram and the sender's address and port number with:

while (socketB->hasPendingDatagrams()) {
  QByteArray datagram;
  datagram...