in reply to testing number of occurrences in a word

Update: Added my %h to prevent false negatives. Thanks to Corion.

This'll really impress teach :) 

perl -e"my %h;" -nle
"++$h{$_}for split'';print'is ',(grep{1<$_}values%h)?'not ':'','an iso
+gram'"
fred
is an isogram
bill
is not an isogram
Terminating on signal SIGINT(2)

[download]
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

In Section Seekers of Perl Wisdom