Does anyone know of a course specifically for programming C/C++ for Arduino.
I think a distinction can be made between learning C/C++ and learning to program an Arduino. All of the Arduino code is C/C++ but not all of the full scope of C/C++ is relevant to an Arduino. The amount of C/C++ that is essential for Arduino programming is probably quite small.
You have not told us what style of learning works for you - whether you prefer a text-book style or a "suck-it-and-see" style.
I like to look at examples (and there are plenty with the Arduino IDE) and then if I see something I don't understand I can spend some time with Google, etc. learning about it.
I suspect there is no shortage of online tutorials for Arduino programming and for C/C++ programming.
The advantage of the examples is that it brings you in contact with the things that are specific to the Arduino at an early stage. And (for obvious reasons) they do not involve irrelevant C/C++ stuff. However I am not saying that the examples illustrate best-practice C/C++ coding. Many of them fall short of that. But they get the job done.
...R