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

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

The C translation of ch-2.pl could have been quite tricky to write, mainly on
storage allocation (as usual), we would have needed a dynamic array of
solutions; but I bodged it with a static array and an assertion check
assert( n < MAXSOLS )..

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].