in reply to testing number of occurrences in a word
I do not know what a isogram is. But maybe this is what you search.
$_ = <>; my %h; $h{$_}++ for ( split // ); my $not_isog = () = grep $_ > 1, values %h; print "$_ is ", $not_isog ? 'not ' : '', "isog\n";
Boris
In Section
Seekers of Perl Wisdom