Programming Perl, 4th Edition

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";