robust way to traverse an array

Question

I had the data in XML file i.e.

<domain>  
   <host>xyz</host>  
   <key>keeeeeeeeeey</key>  
</domain>
<domain>
  <host>xyz</host>  
   <key>keeeeeeeeeey</key> 
</domain>

From that xml I created an array for robustness had I knew how to find that using xml I would have done so but lack of my knowledge I converted that xml file into array using:

 $json = json_encode($xml); 
 $array = json_decode($json,TRUE);`

Below is my array:

Array
(
    [domain] => Array
        (
            [0] => Array
                (
                    [host] => bdbdfbdvbdbdfbdfbf.net
                    [key] => 933f416350de1a955544b30b5bb7ca09cfa2311101a22972320cc4c7af2ecedc03f36b8a48961ef938972478592a1e261819052b51c09a45cf805663f83cb2c0233969255a2c3e2e7e212a295a247b785d41
                )

            [1] => Array
                (
                    [host] => bdev1vvvvvvveinf.net
                    [key] => 933f416350de1a955544b30b5bb7ca09cfa2311101a22972320cc4c7af2ecedc03f36b8a48961ef938972478592a1e261819052b51c09a45cf805663f83cb2c0233969255a2c3e2e7e212a295a247b785d41
                )

            [2] => Array
                (
                    [host] => bdev1.aaaaaaaaureinf.net
                    [key] => 933f416350de1a955544b30b5bb7ca09cfa2311101a22972320cc4c7af2ecedc03f36b8a48961ef938972478592a1e261819052b51c09a45cf805663f83cb2c0233969255a2c3e2e7e212a295a247b785d41
                )

            [3] => Array
                (
                    [host] => bdennnnnnnninf.net
                    [key] => 933f416350de1a955544b30b5bb7ca09cfa2311101a22972320cc4c7af2ecedc03f36b8a48961ef938972478592a1e261819052b51c09a45cf805663f83cb2c0233969255a2c3e2e7e212a295a247b785d41
                )

            [4] => Array
                (
                    [host] => bdeveewerwerwerwerreinf.net
                    [key] => 933f416350de1a955544b30b5bb7ca09cfa2311101a22972320cc4c7af2ecedc03f36b8a48961ef938972478592a1e261819052b51c09a45cf805663f83cb2c0233969255a2c3e2e7e212a295a247b785d41
                )

        )

)

I want a robust loop through which if I pass the host name it returns the key. Can anyone please throw some light? The size of the array could grow to 100 000 000 plus entries.

Answer 1

Change your array to look like:

$data = array('domain' => array(
  'bdbdfbdvbdbdfbdfbf.net' => '933...',
  'bdev1vvvvvvveinf.net' => '933...',
));

Then you can do this:

echo $data['domain']['bdbdfbdvbdbdfbdfbf.net'];

There is no "robust" way to do it with your current array. You'd have to search through the entire thing:

function get_key($data, $host)
{
    foreach ($data['domain'] as $domain)
    {
      if ($domain['host'] == $host)
        return $domain['key'];
    }
}

Given this new information:

The size of the array could grow to 100 000 000 plus entries.

I retract the usefulness of this answer, as the entire concept of using any plain text format, including XML or a serialized PHP key-value array, to store this amount of data is just crazy.

You should store the data in a database with the domain indexed. Even an sqlite database would be a major upgrade from a linear probe of a text file.

Of course there are ways to store the data in a custom format that is optimized, but there's really no good reason to reinvent something a database can easily do.