Time for action – setting up the client

When the user has provided the server's address and port and has chosen a username, he/she can connect to the server:

void TcpClient::on_connect_clicked()
{
  //...
  if (m_socket->state() != QAbstractSocket::ConnectedState) {
    m_socket->connectToHost(ui->address->text(), ui->port->value());
    ui->chat->insertPlainText("== Connecting...\n");
  }
  //...
}

What just happened?

The private member variable m_socket holds an instance of QTcpSocket. If this socket is already connected, nothing happens. Otherwise, the socket is connected to the given address and port by calling connectToHost(). Besides the obligatory server address and port number, you can pass a third argument to define the mode in which the socket will be opened. For possible values, you can use OpenMode just like we did for QIODevice. Since this call is asynchronous, we print a notification to the chat, so that the user is informed that...