Need example of localeconv and localeconv_l

[James E Keenan]

For heuristic purposes I need to locate a *short* C program which 
exercises the localeconv and localeconv_l functions described in man 3 
localeconv.

I'm looking for something which will print a simple statement to STDOUT 
if and when each of these functions is present.  I'll be running it on 
FreeBSD to demonstrate the presence of both on that OS.  Then I'll run 
it on Linux to demonstrate the absence of localeconv_l therein.

I've conducted DDG search and found many pages with the man page, but 
I'm looking for a beginner-level C program as an example and haven't 
found one.  Any link or example would be greatly appreciated.

Thank you very much.
Jim Keenan