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Hmmmm. why do you teach arrays before containers? And why is so little if any time spent on the std:: containers (ctrl + f deque returns nothing).

The word template is mentioned 3 times, and never once on how to write your own basic templates (no, that's should not be considered advanced).

Finally, why do you keep using the `.open` member function for your streams rather than specifying the file path in the constructor and then testing the validity of the whole stream rather than individual flags.

ie:

    std::ofstream ofs { "my_file" };
    if(ofs) { ///sucess...

You also don't even begin to touch on the standard algorithms. Take for example the book "Accelerated C++". It's only 300 pages, but it has the reader writing modern code with containers and standard algorithms with in the first few pages. It's a much better approach in my opinion.