Question

Okay, not sure where to ask this, but I’m a beginner programmer, using Perl. I need to create an array of an array, but I’m not sure if it would be better use array/hash references, or array of hashes or hash of arrays etc.

I need an array of matches: @totalmatches

Each match contains 6 elements(strings):

@matches = ($chapternumber, $sentencenumber, $sentence, $grammar_relation, $argument1, $argument2)

I need to push each of these elements into the @matches array/hash/reference, and then push that array/hash/reference into the @totalmatches array.

The matches are found based on searching a file and selecting the strings based on meeting the criteria.

QUESTIONS

1. Which data structure would you use?

2. Can you push an array into another array, as you would push an element into an array? Is this an efficient method?

3. Can you push all 6 elements simultaneously, or have to do 6 separate pushes?

4. When working with 2-D, to loop through would you use:

   foreach (@totalmatches) {
   foreach (@matches) {
   …
   }
   }

Thanks for any advice.

Answer 1

Do not push one array into another array.
Lists just join with each other into a new list.

Use list of references.

#create an anonymous hash ref for each match
$one_match_ref = {
     chapternumber => $chapternumber_value, 
     sentencenumber => $sentencenumber_value, 
     sentence => $sentence_value,
     grammar_relation => $grammar_relation_value, 
     arg1 => $argument1, 
     arg2 => $argument2
};

# add the reference of match into array.
push @all_matches, $one_match_ref;

# list of keys of interest
@keys = qw(chapternumber sentencenumber sentence grammer_relation arg1 arg2);
# walk through all the matches.
foreach $ref (@all_matches) {
    foreach $key (@keys) {
        $val = $$ref{$key};

    }
    # or pick up some specific keys
    my $arg1 = $$ref{arg1};
}