获取客户端IP

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<?php


function getip() {
if (isset($_SERVER)) {
    if (isset($_SERVER[HTTP_X_FORWARDED_FOR])) {
     $realip = $_SERVER[HTTP_X_FORWARDED_FOR];
    } elseif (isset($_SERVER[HTTP_CLIENT_IP])) {
     $realip = $_SERVER[HTTP_CLIENT_IP];
    } else {
     $realip = $_SERVER[REMOTE_ADDR];
    }
} 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");
    }
}
return $realip;
}

$ip=getip();
echo "$ip";
?>


php函数——动态调用函数
函数定义：    function A（形式参数列表）{       函数体；       return(返回值)}    function B（形式参数列表）{       函数体；       return(返回值)}函数调用    变量名=A    变量名（实参列表）    变量名=B     变量名（实参列表）
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