>      The title looks bad, sorry. I have a great admiration for Gnu in
> general, but there shouldn't be a thing named "Gnu C". There is C and
> there is a C standard and it is not set by Gnu. Maybe there is no other
> ressource on the web. However, when looking at this web resource I see
> it refers to C99 and Gnu extensions and this seems very outdated.

>      In the mean time we had C11 and now the current standard is C17
> which corrects some errors of C11. The C compilers and C libraries
> nowadays are working on implementing the next standard, C21, IIRC.

>      The GU C resource I found on the web also states that GCC is the
> "Gnu Compiler Collection", but, a few years ago, for the second time in
> history, GCC has divorced from the FSF, because of issues with RMS.

>      In general there are two references for C programming: the C
> standard and the POSIX standard. All OSes aim to more or less comply to
> both, and I recommend avoiding as much as possible GNU extensions or
> whatever extension.

>      Refering to the standard is not the proper way of learning though.
> I consider the best way is to take lessons, and the second best way is
> to use a good book. A book about C only, not "C and C++".