A very quick glance suggests to me that the only thing C++ specific there is the filename extension (although a C compiler would do a more thorough check than I do; and faster, even!)

And the single-line comments, if not using a C99-compliant compiler. I wouldn't be surprised if he was using Visual C++ and had to change the extension to support a comment syntax that doesn't make you want to strangle yourself.

By the way, supposedly, he wrote this "years ago".

Was going to comment exactly the same thing