Arrays of Hashes
An array of hashes is useful when you have a bunch of records that you'd like to access sequentially, and each record itself contains key/value pairs. Arrays of hashes are used less frequently than the other structures in this chapter.
Composition of an Array of Hashes
You can create an array of anonymous hashes as follows:
@AoH = ( { husband => "barney", wife => "betty", son => "bamm bamm", }, { husband => "george", wife => "jane", son => "elroy", }, { husband => "homer", wife => "marge", son => "bart", }, );
To add another hash to the array, you can simply say:
push @AoH, { husband => "fred", wife => "wilma", daughter => "pebbles" };
Generation of an Array of Hashes
Here are some techniques for populating an array of hashes. To read from a file with the following format:
husband=fred friend=barney
you could use either of the following two loops:
while ( <> ) { $rec = {}; for $field ( split ) { ($key, $value) = split /=/, $field; $rec->{$key} = $value; } push @AoH, $rec; } while ( <> ) { push @AoH, { split /[\s=]+/ }; }
If you have a subroutine get_next_pair
that
returns key/value pairs, you can use it to stuff
@AoH
with either of these two loops:
while ( @fields = get_next_pair() ) { push @AoH, { @fields }; } while (<>) { push @AoH, { get_next_pair($_) }; }
You can append new members to an existing hash like so:
$AoH[0]{pet} = "dino"; $AoH[2]{pet} = "santa's little helper";
Access and Printing of an Array of Hashes
You can set a key/value pair of a particular hash as ...
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