Hello Ken, I can't thank you enough for the time and effort spent on such detailed and fantastic analysis. This is your second answer to my two posts here on perl monks and I can say for sure that I have learnt so much from your answers than I could ever have by reading a book.

In regards to my use of hash reference instead of hash was basically to get a hang of hash reference iteration. I have been reading references lately and thought would be a good idea to practice it here.

Your following points were extremely valuable and helpful: 

- #!/usr/bin/env perl -l for new lines
- Using my ($name, $code, $count) = split /\Q$sep/; 
instead of array and hard coding separator
- my @codes = sort keys %codes_found; 
Instead of looping through the hash
- Using for instead of foreach
- print join $sep => $name, map { $data{$name}{$_} || '' } @codes; Thi
+s is exactly what I was looking for. Idiomatic and very readable.

[download]

One follow up question, I never seen fat comma (=>) used in join. Is this because we wanted the $sep to be quoted and fat comma will do that for us?

Also, in the line

print join $sep => $name, map { $data{$name}{$_} || '' } @codes;

Why does auto-vivification does not occur here? What makes perl decide to go the OR (||) route to map null string to join function?

Thank you again. I know I have a long way to go in learning perl and will look forward to your guidance here on perl monks.

Regards, Jaypal

In reply to Re^2: Print something when key does not exist by jaypal
in thread Print something when key does not exist by jaypal

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