But libraries come with examples which give you an idea of how to use the library.
It sounds like you are suggesting that I shouldn't bother until I have the knowledge to write my own libraries.
I do actually do a lot of reading about C++, but it is a massive subject.
I'm actually a structural engineer of 30 years. It is quite common for graduates to finish their 4 year degrees and come to work knowing nothing but theory. Until they get some experience they are useless.
I'm in the position of trying to do both at the same time. I'm reading about C++, but also working on projects.
It's an up hill struggle but I'll get there.
This forum is really helpful because unlike when I was a graduate, I don't have experienced people to talk to when I get stuck.