The arrow operator and identifiers with leading underscores seem to be glossed over or skipped fairly often in education. It's intimidating to look at code that uses them if you don't know what they are.
I always thought that "all identifiers with a leading underscore were reserved". I just consciously ignored it, and have never had a problem in years. But I was also always using member variable names like "_children", "_childCount", etc, not "_Children".
In fact, here's a reference: http://msdn.microsoft.com/en-us/library/e7f8y25b(v=vs.80).as... (It's in a "Microsoft Specific" block but says it's part of the ANSI C standard.) It applies to C, and it also applies to identifiers staring with two underscores.
The C Standard reserves identifiers starting with a leading underscore for the system implementation (C standard library, Posix libraries, etc). They aren't meant for use by user code (or rather, you can use them, but they might conflict with system defined identifiers).