Re: Hash dereferencing in a loop

In your first version $hashRef{$key}, you make use of %hashRef which is not declared. Change it to $hashRef->{$key} and you should be fine. No need to do a copy as in your workaround which would be wasteful if the hash is large.

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Re^2: Hash dereferencing in a loop by locked_user sundialsvc4 (Abbot) on Jun 08, 2013 at 14:21 UTC
Also, you may encounter “double-$” syntax: `$$hashref{$key}`. The two are equivalent, and notice in this case that the `->` symbol does not appear. Recommend that you consistently use one or the other (your choice) in your programs. (Double-$ is less common.) Also note that, in cases where a sequence of `->` symbols would technically be required, to reference elements of a hashref that contains hashrefs, Perl allows the additional ones to be omitted.

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Re^2: Hash dereferencing in a loop
by locked_user sundialsvc4 (Abbot) on Jun 08, 2013 at 14:21 UTC

Also, you may encounter “double-$” syntax: $$hashref{$key}.

The two are equivalent, and notice in this case that the -> symbol does not appear. Recommend that you consistently use one or the other (your choice) in your programs. (Double-$ is less common.)

Also note that, in cases where a sequence of -> symbols would technically be required, to reference elements of a hashref that contains hashrefs, Perl allows the additional ones to be omitted.