在PHP中如何获取用户的真实IP

/**

 * 获得用户的真实IP地址

 *

 * @access  public

 * @return  string

 */

function real_ip()

{

    static $realip = NULL;

    if ($realip !== NULL)

    {

        return $realip;

    }

    if (isset($_SERVER))

    {

        if (isset($_SERVER['HTTP_X_FORWARDED_FOR']))

        {

            $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);

            /* 取X-Forwarded-For中第一个非unknown的有效IP字符串 */

            foreach ($arr AS $ip)

            {

                $ip = trim($ip);

                if ($ip != 'unknown')

                {

                    $realip = $ip;

                    break;

                }

            }

        }

        elseif (isset($_SERVER['HTTP_CLIENT_IP']))

        {

            $realip = $_SERVER['HTTP_CLIENT_IP'];

        }

        else

        {

            if (isset($_SERVER['REMOTE_ADDR']))

            {

                $realip = $_SERVER['REMOTE_ADDR'];

            }

            else

            {

                $realip = '0.0.0.0';

            }

        }

    }

    else

    {

        if (getenv('HTTP_X_FORWARDED_FOR'))

        {

            $realip = getenv('HTTP_X_FORWARDED_FOR');

        }

        elseif (getenv('HTTP_CLIENT_IP'))

        {

            $realip = getenv('HTTP_CLIENT_IP');

        }

        else

        {

            $realip = getenv('REMOTE_ADDR');

        }

    }

    preg_match("/[\d\.]{7,15}/", $realip, $onlineip);

    $realip = !empty($onlineip[0]) ? $onlineip[0] : '0.0.0.0';

    return $realip;

}

如果大家还有别的方式的话，可以一起交流哦。

下面再给大家一些常用的PHP函数，以后说不定能用上哦。

 <?php

 class common {

  /*

      * 获取服务器的时区

      */

      function server_timezone(){

          if(function_exists('date_default_timezone_get')){

            return date_default_timezone_get();

          }else{

              return date('Z')/3600;

          }

      }

     /*

      * 获取字符串的长度

      */

     function str_len($str){

         $length = strlen(preg_replace('/[\x00-\x7F]/','',$str));

         if($length){

             return strlen($str)-$length + intval($length/3)*2;

         }else{

             return strlen($str);

         }

     }

     /*

      * 截取字符串

      * $str 将要截取的字符换

      * $length 截取字符串的长度

      * $append 是否添加省落号 默认是

      */

     public function sub_str($str,$length=0,$append = true){

             $str = trim($str);

             $strlength = strlen($str);

             if($length == 0 || $length >= $strlength){

                  return $str;

             }elseif( $length < 0){

                  $length = $length + $strlength;

                  if($length < 0){

                      $length = $strlength;

                  }

             }

             if(function_exists("mb_substr")){

                 $newstr = mb_substr($str,0,$length,"gb2312");

             }elseif (function_exists('iconv_substr')){

                 $newstr = iconv_substr($str, 0, $length, "gb2312");

             }else

             {

                 $newstr = substr($str, 0, $length);

             }

             if ($append && $str != $newstr){

                 $newstr .= '...';

             }

             return $newstr;

     }

     /*获得当前格林威治时间的时间戳

      * @return  integer

     */

     function getTime(){

         return (time() - date("Z"));

     }

     /*

      * 创建像这样的查询条件 in('','');

      */

     function db_create_in($itme_list,$feild_name){

         if(empty($itme_list)){

             return $feild_name."IN('')";

         }else{

             if(!is_array($feild_name)){

                 $itme_list = explode(",",$itme_list);

             }

             $itme_list = array_unique($itme_list);

             $itme_list_tmp ="";

             foreach($itme_list as $item){

                 if(!$item($item)){

                     $itme_list_tmp .= $itme_list_tmp?",'$item'":"'$item'";

                 }

             }

             if(empty($itme_list_tmp)){

                 return $feild_name."IN('')";

             }else{

                 return $feild_name."IN('.$itme_list_tmp.')";

             }

         }

     }

     /*

      * 检查时间的格式是否正确

      */

      function is_time($time){

          $pattern = '/[\d]{4}-[\d]{1,2}-[\d]{1,2}\s[\d]{1,2}:[\d]{1,2}:[\d]{1,2}/';

          return preg_match($pattern,$time);

      }

 }

 ?>