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

ch-1.c produces identical (non-debugging) output to my Perl original.

It uses the command-line argument processing module args.[ch], and the
integer-list parsing (parseints.[ch]) module, and the integer-list printing
module (printarray.[ch]) from earlier challenges, tweaked slightly.

Note that it's not a direct translation of the Perl solution because that
involves joined strings and then storing a set of such joined strings.
Instead it does it the obvious low-tech way: finding duplicate arrays and
deleting them.

I didn't have time to try ch-2.pl into C, although that should be
straightforward using mktime() and friends like I did in challenge 176.
Maybe I'll do that a bit later.