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);

      }

 }

 ?>