ip_class.php

<?php

function checkIPClass($ip) {
    $ipLong = ip2long($ip);
    if ($ipLong == -1 || $ipLong === FALSE) {
        return null;
    }
    $ipBinaryString = sprintf('%b', $ipLong);
    $ipBinaryString = str_pad($ipBinaryString, 32, '0', STR_PAD_LEFT);
    
    $whichClass = null;
    $classFeatureMapper = array(
        // A类ip
        '0' => 'A',
        // B类ip
        '10' => 'B',
        // C类ip
        '110' => 'C',
        // D类ip
        '1110' => 'D',
        // E类ip
        '1111' => 'E',
    );
    foreach ($classFeatureMapper as $feature => $ipClass) {
        if (strpos($ipBinaryString, '' . $feature) === 0) {
            $whichClass = $ipClass;
            break;
        }
    }

    return $whichClass;
}

$ipList = array(
    "127.0.0.1",
    "127.101.0.1",
    "192.168.0.1",
    "202.168.3.4",
    "128.127.7.8",
    "224.233.56.7",
);

$nodeList = array();

foreach ($ipList as $ip) {
    $whichClass = checkIPClass($ip);
    if ($whichClass === null) {
        echo "$ip not in any class\n";
        continue;
    }
    if (!array_key_exists($whichClass, $nodeList)) {
        $nodeList[$whichClass] = array();
    }
    array_push($nodeList[$whichClass], $ip);
}

echo json_encode(array('nodes' => array_values($nodeList))) . "\n";