Like this?

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11148100
use warnings;

for ( glob join '-', ('{-,}42') x 3 )
  {
  my ($X, $Y, $Z) = /(-?\d+)-(-?\d+)-(-?\d+)/;
  printf "%11s => %3s %3s %3s\n", $_, $X, $Y, $Z;
  }
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Outputs:

-42--42--42 => -42 -42 -42
 -42--42-42 => -42 -42  42
 -42-42--42 => -42  42 -42
  -42-42-42 => -42  42  42
 42--42--42 =>  42 -42 -42
  42--42-42 =>  42 -42  42
  42-42--42 =>  42  42 -42
   42-42-42 =>  42  42  42
[download]