下面是一个很好的获取用户IP地址的干净代码示例。

$ip = $_SERVER['HTTP_CLIENT_IP'] 
   ? $_SERVER['HTTP_CLIENT_IP'] 
   : ($_SERVER['HTTP_X_FORWARDED_FOR'] 
        ? $_SERVER['HTTP_X_FORWARDED_FOR'] 
        : $_SERVER['REMOTE_ADDR']);

下面是一个使用elvis操作符的简短版本:

$_SERVER['HTTP_CLIENT_IP'] 
   ? : ($_SERVER['HTTP_X_FORWARDED_FOR'] 
   ? : $_SERVER['REMOTE_ADDR']);

下面是一个使用isset删除通知的版本(谢谢你，@shasi kanth):

$ip = isset($_SERVER['HTTP_CLIENT_IP']) 
    ? $_SERVER['HTTP_CLIENT_IP'] 
    : (isset($_SERVER['HTTP_X_FORWARDED_FOR']) 
      ? $_SERVER['HTTP_X_FORWARDED_FOR'] 
      : $_SERVER['REMOTE_ADDR']);

这可以通过使用名为$_SERVER的GLOBAL变量来简单地完成。

$_SERVER是一个属性名为REMOTE_ADDR的数组。

就像这样分配它:

$userIp = $_SERVER['REMOTE_ADDR'];

或者直接使用它像echo $_SERVER['REMOTE_ADDR']; 或者echo ($_SERVER['REMOTE_ADDR']);

它应该包含在$_SERVER['REMOTE_ADDR']变量中。

你可以使用下面的函数

function get_client_ip() {
    $ipaddress = '';
    if (isset($_SERVER['HTTP_CLIENT_IP']))
        $ipaddress = $_SERVER['HTTP_CLIENT_IP'];
    else if(isset($_SERVER['HTTP_X_FORWARDED_FOR']))
        $ipaddress = $_SERVER['HTTP_X_FORWARDED_FOR'];
    else if(isset($_SERVER['HTTP_X_FORWARDED']))
        $ipaddress = $_SERVER['HTTP_X_FORWARDED'];
    else if(isset($_SERVER['HTTP_FORWARDED_FOR']))
        $ipaddress = $_SERVER['HTTP_FORWARDED_FOR'];
    else if(isset($_SERVER['HTTP_FORWARDED']))
        $ipaddress = $_SERVER['HTTP_FORWARDED'];
    else if(isset($_SERVER['REMOTE_ADDR']))
        $ipaddress = $_SERVER['REMOTE_ADDR'];
    else
        $ipaddress = 'UNKNOWN';
    return $ipaddress;
}

快速解决方案(无错误)

function getClientIP():string
{
    $keys=array('HTTP_CLIENT_IP','HTTP_X_FORWARDED_FOR','HTTP_X_FORWARDED','HTTP_FORWARDED_FOR','HTTP_FORWARDED','REMOTE_ADDR');
    foreach($keys as $k)
    {
        if (!empty($_SERVER[$k]) && filter_var($_SERVER[$k], FILTER_VALIDATE_IP))
        {
            return $_SERVER[$k];
        }
    }
    return "UNKNOWN";
}

这个函数很紧凑，可以在任何地方使用。但是!

别忘了这一点!在这类函数或代码块中，不能保证记录用户的真实IP地址，因为有些用户可以使用代理或其他安全网关来实现不可见或无法跟踪

PHP函数:

function GetIP()
{
    if ( getenv("HTTP_CLIENT_IP") ) {
        $ip = getenv("HTTP_CLIENT_IP");
    } elseif ( getenv("HTTP_X_FORWARDED_FOR") ) {
        $ip = getenv("HTTP_X_FORWARDED_FOR");
        if ( strstr($ip, ',') ) {
            $tmp = explode(',', $ip);
            $ip = trim($tmp[0]);
        }
    } else {
        $ip = getenv("REMOTE_ADDR");
    }
    return $ip;
}

用法:

$IP = GetIP();或直接GetIP();