Short Style for Arrays

search_params.php

<?php

/**
 * Used for searching nested arrays
 * Instead of `$user['profile']['avatar']['large']`
 * It allows for `search_params($user, 'profile.avatar.large')
 * 
 * Benefits
 * - It checks if the value is set. if not returns null
 * - makes sure the array is there.
 *  | for instance, what if an API changes
 *
 * @param string $haystack 
 * @param string $needle 
 * @return void
 * @author Baylor Rae'
 */
function search_params($haystack, $needle) {
    $keys = explode('.', $needle);
    $output = $haystack;
    $changed = false;

    foreach( $keys as $key ) {
        if(isset($output[$key])){
            $output = $output[$key];
            $changed = true;

            // End of array chain?
            if( !is_array($output) )
              break;

        }else { // no matches? no results
          $changed = false;
          break;
        }
    }

    return $changed ? $output : null;
}

usage+functions.php

<?php

function _post($needle) {
  return search_params($_POST, $needle);
}

function _get($needle) {
  return search_params($_GET, $needle);
}

// Usage
$username = _post('user.username') || false;
$thumbnail = _post('user.profile.thumbnail.large') || 'default.png';

I used a simular appraoch to get data from an array, but i was wondering do you have an idea to use the same approach to change the data in a array.