In this case the code is likely pretty messy. The repo explains that it was ported from a Flash game and a lot of the bad hacks used to make it work in Flash were ported to C++ more or less verbatim.
> For example, maybe my worst programming habit is declaring temporary variables like i, j and k as members of each class, so that I didn’t have to declare them inside functions (which is annoying to do in flash for boring reasons). This led to some nasty and difficult to track down bugs, to say the least. In entity collision in particular, several functions will share the same i variable. Infinite loops are possible.
Does anyone know what are these boring reasons? I've used AS2 and AS3 extensively and don't remember this ever being an issue