Platform independent Qt5 way to get open TCP port

Question

Is there a platform independent way in Qt to get an unused TCP port? I have a need to launch an existing application which must be given an open TCP port in order for it to work.

Answer 1

use QTcpServer is easier way.

bool QTcpServer::listen(const QHostAddress & address = QHostAddress::Any, quint16 port = 0)

If port is 0, a port is chosen automatically, then you use quint16 QTcpServer::serverPort() const to get the "idle" port

then close your Tcp Server

OR

generate a ramdom port, use QTcpSocket to connect it(local connection)

1. if connected, your port is QTcpSocket::localPort() and close this tcp socket
2. if not connected, your port is random port;