Every
programming language has a
standard for naming its
source files.
Python does
.py,
Prolog (along with
Poland and
perl4) does
.pl,
C does
.c for
source and
.h for
interface,
sh does
.sh.
What about C++? Well, if ever you see any of the following extensions, know you're onto a C++ file (sorry, translation unit). Well, at least you might be...
NOTE: This list makes no pretenses of completeness!