Data Structures

The Data Structures are of a bit complex to understand but it very powerful in storing huge records. Have a look at the data structures explained very easy.

Arrays of Arrays

There are many kinds of nested data structures. The simplest kind to build is an array of arrays, also called a two-dimensional array or a matrix.

    
    @array = (
        ['a','b'],
        ['c','d'],
        ['e','f']
        );

        print $array[1][0]; #result c;

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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.

    @array = (
        {
            'a'=>'b',
            'b'=>'c'
        },
        {
            'c'=>'d',
            'd'=>'e'
        },
        {
            'e'=>'f',
            'f'=>'g'
        }
    );

    print $array[1]{c}; #result d;

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Hashes of Arrays

Use a hash of arrays when you want to look up each array by a particular string rather than merely by an index number.

    %hash = (
        "1" => ['a','b'],
        "2" => ['c','d'],
        "3" => ['e','f'],
    
);

  print $hash{1}[0]; result a

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Hashes of Hashes

A multidimensional hash is the most flexible of Perl's nested structures. It's like building up a record that itself contains other records.

  %hash = (
    "1" => {
                'a'=>'b',
                'b'=>'c'
           },
    "2" => {
                'c'=>'d',
                'd'=>'e'
           },
    "3" => {
                'e'=>'f',
                'f'=>'g'
           }
      );

  print $hash{2}{d}; #result e

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Moved from Q & A to Meditations by Arunbear

In reply to Learn Data Structures easy by l.frankline

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