PHP 获取当前客户端的IP地址，并判断是否在1.1.1.1 - 255.255.255.254区间

答案

function getip()
{
    $unknown = 'unknown';
    if (isset($_SERVER['HTTP_X_FORWARDED_FOR']) && $_SERVER['HTTP_X_FORWARDED_FOR'] && strcasecmp($_SERVER['HTTP_X_FORWARDED_FOR'], $unknown)) {
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    } elseif (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], $unknown)) {
        $ip = $_SERVER['REMOTE_ADDR'];
    }
    /*
    处理多层代理的情况
    或者使用正则方式：$ip = preg_match("/[\d\.]{7,15}/", $ip, $matches) ? $matches[0] : $unknown;
    */
    if (false !== strpos($ip, ','))
        $ip = reset(explode(',', $ip));
    return $ip;
}
$client_ip = getip();
$client_ip = sprintf('%u', ip2long($client_ip));   //64位系统无压力
/**
 * plan A
 */
$range_min = sprintf('%u', ip2long('1.1.1.1'));
$range_max = sprintf('%u', ip2long('255.255.255.255'));
/**
 * plan B
 */
$range_min = bindec(decbin(ip2long('1.1.1.1')));
$range_max = bindec(decbin(ip2long('255.255.255.255')));
if ($client_ip >= $range_min and $client_ip <= $range_max) {
    echo 'true';
} else {
    echo 'false';
}