how to add a new c++ class in widget application

[d_stranz]

Maybe you should start with the Qt for Beginners tutorial and working through some of the official Qt tutorials and examples that come with your distribution. And you can refer to the Qt Creator manual to learn how to manage projects and files.

These resources are a much better way to learn Qt than watching YouTube videos.

As for QThread, it hasn't changed much between Qt4 and Qt5, so whatever information you got from the YouTube video is probably wrong. QThread uses QObject as a base class in both Qt versions.

[rolly4444]

thank you so much