You could just create a class for all the input:
class Input
{
public:
static bool isMainLoopActive;
static bool isMoveRightPressed;
...
}
then anywhere you can access them e.g. input.isMainLoopActive
Edit: I slightly missunderstood the question, but you could still use this.
Edit 2: Im no c++ guru so this may be completely wrong.
The main difference between a class and a struct is that members within a struct are automatically public.