［转］PHP获取IP地址

［转自］http://hi.baidu.com/xiamishule/blog/item/dea92c09ef9acc9e0b7b8236.html
源代码：
PHP获取IP的方法有许多种，<br />今天向大家总结了六种方法。
<br />PHP获取IP方法一：
<?php    
function GetIP() {
    if(!empty($_SERVER["HTTP_CLIENT_IP"]))
       $cip = $_SERVER["HTTP_CLIENT_IP"];
    else if(!empty($_SERVER["HTTP_X_FORWARDED_FOR"]))    
       $cip = $_SERVER["HTTP_X_FORWARDED_FOR"];
    else if(!empty($_SERVER["REMOTE_ADDR"]))   
       $cip = $_SERVER["REMOTE_ADDR"];
    else  
       $cip = "无法获取！";
    return $cip;
}
echo GetIP();
?>
<br />PHP获取IP方法二：
<?
error_reporting (E_ERROR | E_WARNING | E_PARSE);
if($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"]){
    $ip = $HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"];
}
elseif($HTTP_SERVER_VARS["HTTP_CLIENT_IP"]){  
    $ip = $HTTP_SERVER_VARS["HTTP_CLIENT_IP"];
}
elseif ($HTTP_SERVER_VARS["REMOTE_ADDR"]){
    $ip = $HTTP_SERVER_VARS["REMOTE_ADDR"];
}
elseif (getenv("HTTP_X_FORWARDED_FOR")){
    $ip = getenv("HTTP_X_FORWARDED_FOR");
}
elseif (getenv("HTTP_CLIENT_IP")){
    $ip = getenv("HTTP_CLIENT_IP");
}
elseif (getenv("REMOTE_ADDR")){
    $ip = getenv("REMOTE_ADDR");
}
else{
    $ip = "Unknown";
}
echo $ip;
?>
<br />PHP获取IP方法三：
<? $iipp = $_SERVER["REMOTE_ADDR"]; echo $iipp; ?>
<br />PHP获取IP方法四：
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