Game developments by example - handle Input Class

[MrMode]

Hello started reading  a book Game development by example, and now read a topic about the handle input class, tried to make code work and it  doesn't, Syntax is ridiculously hard, so just asking for help to understand a code and fix it , to make it work.
 
here is the code in github
https://github.com/M0d3stas/game-by-example-4.git

[NGM88]

"Syntax is ridiculously hard" only proportional to your c++ knowledge. I would recommend improving your c++ rather than trying to simplify the book to your level of c++. Whatever it is that you don't understand in the book, learn it using a good c++ source. This will be a better investment of your time.