PHP Validate Postal Code

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<?php

/**
 * Validate a postal code.
 *
 * @param $value
 *   A postal code as string.
 * @param $country
 *   The country postal code format.
 * @return
 *   TRUE or FALSE if it validates.
 */
function valid_postal_code($value, $country = 'ca') {
  $country_regex = array(
    'uk' => '/\\A\\b[A-Z]{1,2}[0-9][A-Z0-9]? [0-9][ABD-HJLNP-UW-Z]{2}\\b\\z/i',
    'ca' => '/\\A\\b[ABCEGHJKLMNPRSTVXY][0-9][A-Z][ ]?[0-9][A-Z][0-9]\\b\\z/i',
    'it' => '/^[0-9]{5}$/i',
    'de' => '/^[0-9]{5}$/i',
    'be' => '/^[1-9]{1}[0-9]{3}$/i',
    'us' => '/\\A\\b[0-9]{5}(?:-[0-9]{4})?\\b\\z/i',
    'default' => '/\\A\\b[0-9]{5}(?:-[0-9]{4})?\\b\\z/i' // Same as US.
  );
  
  if ( isset($country_regex[$country]) ) {
    return preg_match($country_regex[$country], $value);
  }
  
  return preg_match($country_regex['default'], $value);
}