It would help, in future, if you were to tell us what an "isogram" is; just in case we haven't seen this word since we were in school doing the same assignment you might be doing.

According to a quick websearch:

An isogram is a text that does not repeat a letter.

It seems to me that all you need to do is to break your text up into letters and then check if they are all unique. You could do this latter part by sorting them and then walking the length of the sorted text testing to see if the current letter is the same as the previous; or you could take advantage of the fact that hash keys must be unique...

The second option is faster, but both will be correct. Which ever way you choose, have a go at it and come back if you have any problems.

all the best,

This question and your previous question sound like homework problems. What code do you have for this, and where are you stuck? And what is an "isogram"? Do you mean the isogram? If so, you can restate the problem in easy steps which are translated easily into Perl.

Using the definition of an isogram from wikipedia, let's make it into a golf challenge. Anyone?

(The reasoning being, if it's golfed, it won't be acceptable as a homework solution.)

49, but then again I suck at golf.

sub isogram {
#234567890#234567890#234567890#234567890#234567890
my%h=map{($_,1)}split//,$_[0];keys%h==length$_[0]
}

print "$_ is ", (isogram($_) ? '' : 'not '), "an isogram\n" for @ARGV;
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Duh, johngg had the right idea, except he wasn't greedy enough (nor was I. What's with the $_[0]? Sheesh.):

sub isogram {
#23456789
/(.).*\1/
}

print "$_ is ", (isogram() ? '' : 'not '), "an isogram\n" for @ARGV;
[download]

That makes for 9.

• another intruder with the mooring in the heart of the Perl

Very nice, but your logic is reversed.  Remember, an isogram does NOT have any letters duplicated.

To keep it golfed, either change the caller of the subroutine:

print "$_ is ", (isogram() ? 'not ' : ''), "an isogram\n" for @ARGV;
[download]

or, better yet, the subroutine name:

sub not_isogram {
    # ...
}
print "$_ is ", (not_isogram() ? '': 'not '), "an isogram\n" for @ARGV
+;
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---

s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/

print
   qq{$word },
     $word =~ m{(.).*?\1}
   ? q{is not }
   : q{is },
   qq{an isogram\n};
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Cheers,

JohnGG

Update: Fixed wonky braces/parentheses, thanks tweetiepooh

I like this one. I can actually read it. Some of the closing braces/parenthesis don't seem right though.

Yes, well spotted. My excuse is I was rushing off early to play squash, hence the shonky typing. I'll fix it.

Cheers,

JohnGG

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)
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perl -F// -lane 'my(%x);@x{@F}=();print keys %x==@F?"yes":"no"';
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I'm not sure how I'd count this, as it does the printing, also.

#!/usr/bin/perl -l
$_ = shift;

print"$_ is",(grep$_>1,map++$c{$_},split//)?"n't":'',' an isogram';
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Output:

$ perl isogram.pl greet
greet isn't an isogram

$ perl isogram.pl isogram
isogram is an isogram

$ perl isogram.pl discrete
discrete isn't an isogram
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Update: I wouldn't count it, as /(.).*\1/ is much shorter.

Update 2 I'd still count it as the shortest of the non-regex versions. And here it is as a sub for easier counting:

sub is_iso {
(grep$_>1,map++$c{$_},split//,shift)?1:0
}


$_ = shift;
print "$_ is", ( is_iso($_)? "n't" : '' ), ' an isogram';
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s**lil*;  $*=join'',sort split q**;  s;.*;grr; &&s+(.(.)).+$2$1+; $; =
qq-$_-;s,.*,ahc,;$,.=chop for split q,,,reverse;print for($,,$;,$*,$/)
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You can shorten that further:

sub is_iso {
grep$_>1,map++$c{$_},split//
}
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12 fewer strokes :)

$_ = <>;
my %h;
$h{$_}++ for ( split // );
my $not_isog = () = grep $_ > 1, values %h;
print "$_ is ", $not_isog ? 'not ' : '', "isog\n";
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if ( $word =~ /([\Q$word\E])(?=.*\1)/ ) {
    print "$word is NOT an isogram.\n";
    }
else {
    print "$word is an isogram.\n";
    }
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