title: Auto-detecting active MYSQL port in C++
body: <p>I'm working on a Qt/C++ project, and one of its functions is setting up a MySQL database. That particular bit of code works fine, but one of the things that the user must provide to make it work  is the port that the MySQL process is currently listening on.  This is usually 3306 or 5432, (depending on OS... MySQL usually wants to use 3306 first but I’ve had it try to use the Postgres port on one occasion) but I feel like I need to account for strange configurations. Many users will have no idea what to put in that field unless they know enough about MySQL to know what ports it uses. (most people don't) My target audience for the program is everyone who might want to keep a computerized diary, so it would be nice if the program can find the correct port on its own.  </p>
  
  <p>I could have the program run through a list of commonly-used ports until it finds the right one, (which should work in most setups) but it would be better if it could actually figure out which port to use. That way, there won't be any problems if the user has a bizarre configuration for some reason. </p>
  
  <p>Any idea how I would go about doing this? I've tried googling and I found nothing relevant. </p>