How to close the window correctly?

Question

Qt

I have two windows, the first window is the privacy policy window. The second window opens when you agree to the first window. It is necessary for me that the first window would be closed right after opening of the second. I tried with QApplication::quake and firstclassname::close().
But there is a second problem, the second window does not have time to open.
I moved close to the beginning of the code and to the end and to the middle, Nothing helped.
How to SAFELY CLOSE the window and manage to open the second window.

Answer 1

Read any book on Qt. Save a lot of time and find answers to a thousand more similar questions.