<?php

// validation rules
$postcode_validation = array
(
    'GB' => 'GIR[ ]?0AA|((AB|AL|B|BA|BB|BD|BH|BL|BN|BR|BS|BT|CA|CB|CF|CH|CM|CO|CR|CT|CV|CW|DA|DD|DE|DG|DH|DL|DN|DT|DY|E|EC|EH|EN|EX|FK|FY|G|GL|GY|GU|HA|HD|HG|HP|HR|HS|HU|HX|IG|IM|IP|IV|JE|KA|KT|KW|KY|L|LA|LD|LE|LL|LN|LS|LU|M|ME|MK|ML|N|NE|NG|NN|NP|NR|NW|OL|OX|PA|PE|PH|PL|PO|PR|RG|RH|RM|S|SA|SE|SG|SK|SL|SM|SN|SO|SP|SR|SS|ST|SW|SY|TA|TD|TF|TN|TQ|TR|TS|TW|UB|W|WA|WC|WD|WF|WN|WR|WS|WV|YO|ZE)(\d[\dA-Z]?[ ]?\d[ABD-HJLN-UW-Z]{2}))|BFPO[ ]?\d{1,4}',
    'JE' => 'JE\d[\dA-Z]?[ ]?\d[ABD-HJLN-UW-Z]{2}',
    'GG' => 'GY\d[\dA-Z]?[ ]?\d[ABD-HJLN-UW-Z]{2}',
    'IM' => 'IM\d[\dA-Z]?[ ]?\d[ABD-HJLN-UW-Z]{2}',
    'US' => '\d{5}([ \-]\d{4})?',
    'CA' => '[ABCEGHJKLMNPRSTVXY]\d[ABCEGHJ-NPRSTV-Z][ ]?\d[ABCEGHJ-NPRSTV-Z]\d',
    'DE' => '\d{5}',
    'JP' => '\d{3}-\d{4}',
    'FR' => '\d{2}[ ]?\d{3}',
    'AU' => '\d{4}',
    'IT' => '\d{5}',
    'CH' => '\d{4}',
    'AT' => '\d{4}',
    'ES' => '\d{5}',
    'NL' => '\d{4}[ ]?[A-Z]{2}',
    'BE' => '\d{4}',
    'DK' => '\d{4}',
    'SE' => '\d{3}[ ]?\d{2}',
    'NO' => '\d{4}',
    'BR' => '\d{5}[\-]?\d{3}',
    'PT' => '\d{4}([\-]\d{3})?',
    'FI' => '\d{5}',
    'AX' => '22\d{3}',
    'KR' => '\d{3}[\-]\d{3}',
    'CN' => '\d{6}',
    'TW' => '\d{3}(\d{2})?',
    'SG' => '\d{6}',
    'DZ' => '\d{5}',
    'AD' => 'AD\d{3}',
    'AR' => '([A-HJ-NP-Z])?\d{4}([A-Z]{3})?',
    'AM' => '(37)?\d{4}',
    'AZ' => '\d{4}',
    'BH' => '((1[0-2]|[2-9])\d{2})?',
    'BD' => '\d{4}',
    'BB' => '(BB\d{5})?',
    'BY' => '\d{6}',
    'BM' => '[A-Z]{2}[ ]?[A-Z0-9]{2}',
    'BA' => '\d{5}',
    'IO' => 'BBND 1ZZ',
    'BN' => '[A-Z]{2}[ ]?\d{4}',
    'BG' => '\d{4}',
    'KH' => '\d{5}',
    'CV' => '\d{4}',
    'CL' => '\d{7}',
    'CR' => '\d{4,5}|\d{3}-\d{4}',
    'HR' => '\d{5}',
    'CY' => '\d{4}',
    'CZ' => '\d{3}[ ]?\d{2}',
    'DO' => '\d{5}',
    'EC' => '([A-Z]\d{4}[A-Z]|(?:[A-Z]{2})?\d{6})?',
    'EG' => '\d{5}',
    'EE' => '\d{5}',
    'FO' => '\d{3}',
    'GE' => '\d{4}',
    'GR' => '\d{3}[ ]?\d{2}',
    'GL' => '39\d{2}',
    'GT' => '\d{5}',
    'HT' => '\d{4}',
    'HN' => '(?:\d{5})?',
    'HU' => '\d{4}',
    'IS' => '\d{3}',
    'IN' => '\d{6}',
    'ID' => '\d{5}',
    'IE' => '((D|DUBLIN)?([1-9]|6[wW]|1[0-8]|2[024]))?',
    'IL' => '\d{5}',
    'JO' => '\d{5}',
    'KZ' => '\d{6}',
    'KE' => '\d{5}',
    'KW' => '\d{5}',
    'LA' => '\d{5}',
    'LV' => '\d{4}',
    'LB' => '(\d{4}([ ]?\d{4})?)?',
    'LI' => '(948[5-9])|(949[0-7])',
    'LT' => '\d{5}',
    'LU' => '\d{4}',
    'MK' => '\d{4}',
    'MY' => '\d{5}',
    'MV' => '\d{5}',
    'MT' => '[A-Z]{3}[ ]?\d{2,4}',
    'MU' => '(\d{3}[A-Z]{2}\d{3})?',
    'MX' => '\d{5}',
    'MD' => '\d{4}',
    'MC' => '980\d{2}',
    'MA' => '\d{5}',
    'NP' => '\d{5}',
    'NZ' => '\d{4}',
    'NI' => '((\d{4}-)?\d{3}-\d{3}(-\d{1})?)?',
    'NG' => '(\d{6})?',
    'OM' => '(PC )?\d{3}',
    'PK' => '\d{5}',
    'PY' => '\d{4}',
    'PH' => '\d{4}',
    'PL' => '\d{2}-\d{3}',
    'PR' => '00[679]\d{2}([ \-]\d{4})?',
    'RO' => '\d{6}',
    'RU' => '\d{6}',
    'SM' => '4789\d',
    'SA' => '\d{5}',
    'SN' => '\d{5}',
    'SK' => '\d{3}[ ]?\d{2}',
    'SI' => '\d{4}',
    'ZA' => '\d{4}',
    'LK' => '\d{5}',
    'TJ' => '\d{6}',
    'TH' => '\d{5}',
    'TN' => '\d{4}',
    'TR' => '\d{5}',
    'TM' => '\d{6}',
    'UA' => '\d{5}',
    'UY' => '\d{5}',
    'UZ' => '\d{6}',
    'VA' => '00120',
    'VE' => '\d{4}',
    'ZM' => '\d{5}',
    'AS' => '96799',
    'CC' => '6799',
    'CK' => '\d{4}',
    'RS' => '\d{6}',
    'ME' => '8\d{4}',
    'CS' => '\d{5}',
    'YU' => '\d{5}',
    'CX' => '6798',
    'ET' => '\d{4}',
    'FK' => 'FIQQ 1ZZ',
    'NF' => '2899',
    'FM' => '(9694[1-4])([ \-]\d{4})?',
    'GF' => '9[78]3\d{2}',
    'GN' => '\d{3}',
    'GP' => '9[78][01]\d{2}',
    'GS' => 'SIQQ 1ZZ',
    'GU' => '969[123]\d([ \-]\d{4})?',
    'GW' => '\d{4}',
    'HM' => '\d{4}',
    'IQ' => '\d{5}',
    'KG' => '\d{6}',
    'LR' => '\d{4}',
    'LS' => '\d{3}',
    'MG' => '\d{3}',
    'MH' => '969[67]\d([ \-]\d{4})?',
    'MN' => '\d{6}',
    'MP' => '9695[012]([ \-]\d{4})?',
    'MQ' => '9[78]2\d{2}',
    'NC' => '988\d{2}',
    'NE' => '\d{4}',
    'VI' => '008(([0-4]\d)|(5[01]))([ \-]\d{4})?',
    'PF' => '987\d{2}',
    'PG' => '\d{3}',
    'PM' => '9[78]5\d{2}',
    'PN' => 'PCRN 1ZZ',
    'PW' => '96940',
    'RE' => '9[78]4\d{2}',
    'SH' => '(ASCN|STHL) 1ZZ',
    'SJ' => '\d{4}',
    'SO' => '\d{5}',
    'SZ' => '[HLMS]\d{3}',
    'TC' => 'TKCA 1ZZ',
    'WF' => '986\d{2}',
    'YT' => '976\d{2}'
);

// helper function
function isPostcodeValid($country, $postcode)
{
    // Load Mapping
    global $postcode_validation;

    // Check If Country Exists
    if (!array_key_exists($country, $postcode_validation))
        return false;

    // Check Postcode
    $validation_rule = $postcode_validation[$country];
    return (preg_match("/^$validation_rule$/", $postcode) == 1);
}

// Test
$myCountry = 'US';
$myPostcode = '12345-4321';
var_dump(isPostcodeValid($myCountry, $myPostcode));

?>