Re: Can you spot the problem?

[ambrus]

I wonder weather this code could possibly work in perl6, where the | operator will mean something else (see Exegesis 6).

[TimToady]

Works if you change the all the |s to &s. (Plus you can omit the parens if you're golfing, since junctions now bind tighter than comparisons. Well, okay, you can omit the parens even if you're not golfing.)

[ambrus]

I'd rather leave the |'s and change the comparison from "if ... <256" to "unless ... >255". That way the puzzle still works in perl5.

[Roy Johnson]

I like making it all into one logical return expression, with no conditionals.

Without the two character fix/spoiler:

sub isValidIP {
   return (shift =~ m/^(\d+)\.(\d+)\.(\d+)\.(\d+)$/ and (($1|$2|$3|$4)
+ < 256));
}

Update: I wasn't offering a Perl 6 solution, despite the subthread my response was in. That would be

   return (shift =~ m/^(\d+)\.(\d+)\.(\d+)\.(\d+)$/ and not (($1|$2|$3
+|$4) > 255));