Is it okay to use examples from the documentation in your projects?

Question

Qt

Good evening everyone.
I recently started learning Qt using only documentation and google. Having figured out the main features of the framework and looking at a lot of ready-made works, I decided to write my own small project. One part of this project is the visualization of sorting algorithms using QChart. Since I have not worked with charts in Qt before, and indeed with Qt itself, I have to look at a lot of examples in order to make everything not only working, but also beautiful. Accordingly, I use many pieces of code from the documentation and examples (the Examples tab in the documentation or QtCreator), modifying it to suit my task, in my project. But in this case, can I then call this project my own, if there are 30% of my code there (mostly logic)? Do I then have the right to publish it on, for example, github under my own authorship? May I claim what is my work and add it to my portfolio? Is it normal to learn / study technology and write projects in this way, or should you always try to do everything yourself?
Thank you all in advance for your replies <3

Answer 1

Yes.

Answer 2

Yes, more than half of the programs are assembled from examples.
Developers even have a saying: Which is easier - to collect from examples or to convince the customer that he does not need this feature.