Postal code reverse lookup
<form action="?postalcode">
    <input type="text" name="postalcode" value="" />
    <input type="submit" value="Go" />
</form>
<hr>
IP address reverse lookup
<form action="?ip">
    <input type="text" name="ip" value="" />
    <input type="submit" value="Go" />
</form>
<?php
require_once 'geo_helper/init.php';
if (isset($_GET['postalcode'])):
    //remove whitespace
    $_GET['postalcode'] = str_replace(" ", "", $_GET['postalcode']);
    //regex against the postal code
    if (preg_match("/^([a-ceghj-npr-tv-z]){1}[0-9]{1}[a-ceghj-npr-tv-z]{1}[0-9]{1}[a-ceghj-npr-tv-z]{1}[0-9]{1}$/i", $_GET['postalcode'], $postal_code)):

        $api = new GeoHelperMultiGeocoder();
        $rc = $api->geocode($postal_code[0]);

        //get latitude and longitude 
        $ll = $rc->ll();
        //set up the query
        $url = "http://maps.googleapis.com/maps/api/geocode/json?latlng=$ll&sensor=false";

        $curl = curl_init();
        curl_setopt($curl, CURLOPT_URL, $url);
        curl_setopt($curl, CURLOPT_HEADER, false);
        curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        $curlData = curl_exec($curl);
        curl_close($curl);
        //get the address
        $address = json_decode($curlData, TRUE);

        echo $address['results'][0]['formatted_address'];
    endif;
endif;
if (isset($_GET['ip'])):
    //validate ip
    if (preg_match("/^(([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]).){3}([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/", $_GET['ip'], $ip_address)):


        $api = new GeoHelperMultiGeocoder();
        $rc = $api->geocode($ip_address[0]);

        //get latitude and longitude 
        $ll = $rc->ll();
        //set up the query
        $url = "http://maps.googleapis.com/maps/api/geocode/json?latlng=$ll&sensor=false";

        $curl = curl_init();
        curl_setopt($curl, CURLOPT_URL, $url);
        curl_setopt($curl, CURLOPT_HEADER, false);
        curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        $curlData = curl_exec($curl);
        curl_close($curl);

        $address = json_decode($curlData, TRUE);
        echo $address['results'][0]['formatted_address'];
    endif;
endif;
?>