True, I suppose. How about:

use strict;
use warnings;

my ($str, $nth, $find, $p);

$str = "dsf,sdg,hjhgj,gjkh";
$nth = 3; $find = ',';

$str =~ m/(?:.*?$find){$nth}/g;
$p = pos($str) - length($find);
print substr($str, $p) if $p > -1;
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That doesn't use either one :)