One of the most useful offhand comments that clarified hashes when I was learning Perl is the following gem from the Camel.

A hash lookup is linguistically "of". So for instance you would write: 

$wife{Adam} = "Eve";

[download]
That reads, "The wife of Adam is Eve."

So when you sit down to do a problem, describe it to yourself. Whenever you start saying phrases like, "of", "lookup", "check if we have seen this before", and so on, that is generally an excellent sign that a hash fits, and the above tip is frequently a good guide to naming the hash as well!

In reply to Re (tilly) 2: Hash Variable by tilly
in thread Hash Variable by qball

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