根据ip获取当前所在的城市，这种功能大多用在城市分站中，最近小编做了一个给大家分享一下：

1、获取ip地址

function getip() {
  $realip = "";
  $unknown = "unknown";
  if(isset($_SERVER)){          
       if(isset($_SERVER['HTTP_X_FORWARDED_FOR'])&&!empty($_SERVER['HTTP_X_FORWARDED_FOR'])&&strcasecmp($_SERVER['HTTP_X_FORWARDED_FOR'], $unknown)) {
      $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
      foreach ($arr as $ip) {
        $ip = trim($ip);
        if($ip != 'unknown') {
           $realip = $ip;
           break;
        }
      }          
 }elseif(isset($_SERVER['HTTP_CLIENT_IP'])&&!empty($_SERVER['HTTP_CLIENT_IP'])&&strcasecmp($_SERVER['HTTP_CLIENT_IP'], $unknown)) {
  $realip = $_SERVER['HTTP_CLIENT_IP'];         
 }elseif(isset($_SERVER['REMOTE_ADDR'])&&!empty($_SERVER['REMOTE_ADDR'])&&strcasecmp($_SERVER['REMOTE_ADDR'], $unknown)) {
  $realip = $_SERVER['REMOTE_ADDR'];
 }else{
  $realip = $unknown;
 }
 }else{
  if(getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), $unknown)) {
     $realip = getenv("HTTP_X_FORWARDED_FOR");
     }elseif(getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), $unknown)) {
    $realip = getenv("HTTP_CLIENT_IP");
   }elseif(getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), $unknown)) {
    $realip = getenv("REMOTE_ADDR");
    }else{
    $realip = $unknown;
   }
  }
  $realip = preg_match("/[d.]{7,15}/", $realip, $matches) ? $matches[0] : $unknown;
  return $realip;
 }

2、根据ip地址获取所在的城市

function GetIpLookup($ip = '')
{ 
 if (empty($ip))
 { 
  $ip = GetIp();      
 }        
 $res = @file_get_contents('http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=js&ip=' . $ip);
 if(empty($res))
 {
  return false;        
 } 
 $jsonMatches = array();        
 preg_match('#{.+?}#', $res, $jsonMatches);
 if(!isset($jsonMatches[0])){
   return false;        
 }                
 $json = json_decode($jsonMatches[0], true);        
 if(isset($json['ret']) && $json['ret'] == 1) 
 {            
   $json['ip'] = $ip;
   unset($json['ret']);        
 }else{ 
   return false;
 }        
 return $json;
}

效果图：