Thought I'd also have a go at translating ch-1.pl and ch-2.pl into C..

Both C versions produce identical (non-debugging and debugging)
output to the Perl originals.

ch-1.c has to implement a routine to match /^[charset]+$/, where charset
is the parameter.

These C versions use most of my regular support modules:
- a command-line argument processing module args.[ch],
- a csvlist-of-int parsing module parseints.[ch], and
- an int-array printing module printarray.[ch].