detecting process by pid/process name

I have an App which runs on cross-platform.
each time when the App finished running, it would delete its temprorily generated directories.

This auto-delete function could not implimented in debugger since stopping debugging forcing the program ending.
Therefore I have introduced conditional statement to force the program each time if the deleTempDir() is called, please check the left-over temp dirs.

Since the temp dir is marked by the process id, my idea is to let the deleTempDir() examaine the dir name and check whether such a process is still running.
If process not exists, the temp dir is deleted (because it could be some other debugger-app running parallaly, that's why i cannot delete all temp dirs).

Till now from the documentation from QT i dont find a relevant function which fufills my needs. Is there a function in QT which can check whether a process exists by pid?