function detect_city($ip) {                     $default = 'UNKNOWN';              $curlopt_useragent = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)';                     $url = 'http://ipinfodb.com/ip_locator.php?ip=' . urlencode($ip);          $ch = curl_init();                     $curl_opt = array(              CURLOPT_FOLLOWLOCATION  => 1,              CURLOPT_HEADER      => 0,              CURLOPT_RETURNTRANSFER  => 1,              CURLOPT_USERAGENT   => $curlopt_useragent,              CURLOPT_URL       => $url,              CURLOPT_TIMEOUT         => 1,              CURLOPT_REFERER         => 'http://' . $_SERVER['HTTP_HOST'],          );                     curl_setopt_array($ch, $curl_opt);                     $content = curl_exec($ch);                     if (!is_null($curl_info)) {              $curl_info = curl_getinfo($ch);          }                     curl_close($ch);                     if ( preg_match('{<li>City : ([^<]*)</li>}i', $content, $regs) )  {              $city = $regs[1];          }          if ( preg_match('{<li>State/Province : ([^<]*)</li>}i', $content, $regs) )  {              $state = $regs[1];          }              if( $city!='' && $state!='' ){            $location = $city . ', ' . $state;            return $location;          }else{            return $default;           }                 }

用法：

<?php  $ip = $_SERVER['REMOTE_ADDR'];  $city = detect_city($ip);  echo $city;  ?>