That's an interesting observation about speed, Frank. I'm using VS simply because another person uses it on Windows, although I had noticed that Wolfram has tested gcc on the MacOSX and Linux versions found at http://reference.wolfram.com/language/CCompilerDriver/tutorial/SpecificCompilers.html.

I'll pass your observation along.

I have no clue why gcc wouldn't work from Mathematica. Maybe this is the start of a new thread? Hopefully so, since your speed observation is pretty compelling.

Perfect! Now everything works, to include a functioning executable. Thank you (again), Ilian.

What puzzles me now is that for one person (the one who suggested using an earlier version of Visual Studio and not VS2015), a perfectly functional executable was created WITHOUT the CInclude@"WolframRTL.h" command. Yet for me it was essential.

Or perhaps that person observed that the executable had been created and left it at that --(s)he didn't actually run it, whereas I did (although not at first -- I was initially content with seeing that it had been created). That must be it, the only scenario that makes sense. At last we can close this matter -- it was a very instructive (albeit time-consuming) trip.