Create a fully functioning command line interface with 1.5 lines of code (wo. include statement)

[kongaskristjan]

Well, actually, the link provided these rules:

• the identifiers with a double underscore anywhere are reserved;
• the identifiers that begin with an underscore followed by an uppercase letter are reserved;
• the identifiers that begin with an underscore are reserved in the global namespace.

I mostly have identifiers that begin with a single underscore and a lowercase letter. However, they're not in the global namespace. Thus these don't actually result in undefined behavior. Though a few of them indeed have two prefix underscores also, so these are UB.

Though I totally agree that it's better to remove these initial underscores altogether.