Re: eliding number ranges

A math way: (added two test cases for possible boundary problem)

use strict;
use warnings;

sub elide {
    my ($start,$end) = @_;
    if ((my $diff1 = length($end) - length($start)) > 0) {
        return "$start-$end";
    } elsif ($diff1 == 0) {
        if ($start == $end) {
            return $start;
        } else {
            if ((my $diff2 = length($end) - length($end - $start)) > 0
+) {
                $end %= 10 ** (length($end) - $diff2);
            } 
            return "$start-$end";
        }
    }
}

while ( <DATA> ) {
  print elide( split ' ', $_ ), "\n";
}

__DATA__
1   32
4   19
28  39
34  123
321 321
324 329
325 349
340 509
999 1000
1000 1001
[download]

I tried to do it more math by using log10 to determine length, but that failed the second test case I added, because of rounding issue.

Comment on Re: eliding number ranges Download Code

Replies are listed 'Best First'.
Re: Re: eliding number ranges by Roy Johnson (Monsignor) on Nov 13, 2003 at 19:32 UTC
Have you tried it with `__DATA__ 28 31 199 201` [download] ? To get it to really work, I had to add a loop: `sub elide { my ($start,$end) = @_; if ($end < $start) { ($start, $end) = ($end, $star +t) } elsif ($start == $end) { return $start } if (length($end) > length($start)) { return "$start-$end" } else { my $pow = 1; $pow *= 10 while int($end/$pow) > int($start/$pow); $end %= $pow; } return "$start-$end"; }` [download]	[reply] [d/l] [select]
Re: Re: eliding number ranges by melora (Scribe) on Nov 13, 2003 at 18:47 UTC
I think the math approach is my favorite. The one suggestion I want to make, though, is more explicitly handling the situation where $start is larger than $end. It's not likely, but I've seen so much unlikely data in my time..	[reply]