[marrs]

It might not be that easy to tell. The C++ I write (for myself) is essentially plain C. No templates, dynamic dispatch, constructors, or exceptions. Most of the standard libs I use begin with the letter 'c'.

It uses some C++ features, but it's philosophically much closer to C code.

[pjmlp]

If it only compiles with a C++ compiler, it is C++, regardless of the amount of language features being used.

[marrs]

That's fine, but I don't think that's what people mean when they say C++. I certainly wouldn't call myself a C++ coder and, if I applied for a C++ job, I'm pretty sure that, after I had explained that I don't do exceptions, virtuals, or the STL, I'd be politely shown the door.