Code Postal

<?php
$country_code="US";
$zip_postal="11111";
 
$ZIPREG=array(
	"US"=>"^\d{5}([\-]?\d{4})?$",
	"UK"=>"^(GIR|[A-Z]\d[A-Z\d]??|[A-Z]{2}\d[A-Z\d]??)[ ]??(\d[A-Z]{2})$",
	"DE"=>"\b((?:0[1-46-9]\d{3})|(?:[1-357-9]\d{4})|(?:[4][0-24-9]\d{3})|(?:[6][013-9]\d{3}))\b",
	"CA"=>"^([ABCEGHJKLMNPRSTVXY]\d[ABCEGHJKLMNPRSTVWXYZ])\ {0,1}(\d[ABCEGHJKLMNPRSTVWXYZ]\d)$",
	"FR"=>"^(F-)?((2[A|B])|[0-9]{2})[0-9]{3}$",
	"IT"=>"^(V-|I-)?[0-9]{5}$",
	"AU"=>"^(0[289][0-9]{2})|([1345689][0-9]{3})|(2[0-8][0-9]{2})|(290[0-9])|(291[0-4])|(7[0-4][0-9]{2})|(7[8-9][0-9]{2})$",
	"NL"=>"^[1-9][0-9]{3}\s?([a-zA-Z]{2})?$",
	"ES"=>"^([1-9]{2}|[0-9][1-9]|[1-9][0-9])[0-9]{3}$",
	"DK"=>"^([D-d][K-k])?( |-)?[1-9]{1}[0-9]{3}$",
	"SE"=>"^(s-|S-){0,1}[0-9]{3}\s?[0-9]{2}$",
	"BE"=>"^[1-9]{1}[0-9]{3}$"
);
 
if ($ZIPREG[$country_code]) {
 
	if (!preg_match("/".$ZIPREG[$country_code]."/i",$zip_postal)){
		//Validation failed, provided zip/postal code is not valid.
	} else {
		//Validation passed, provided zip/postal code is valid.
	}
 
} else {
 
	//Validation not available
 
}
?>

– source: http://www.pixelenvision.com/1708/zip-postal-code-validation-regex-php-code-for-12-countries/