php获取二级域名

<?php
function getSecondLevelDomain($url) {
    $parsedUrl = parse_url($url);
    $host = $parsedUrl['host'];
    
    // 分割主机名以获取二级域名
    $domainParts = explode('.', $host);
    
    // 假设顶级域名是两个部分（例如 .com, .org）
    if (count($domainParts) > 2) {
        $secondLevelDomain = $domainParts[count($domainParts) - 3];
        return $secondLevelDomain;
    }
    
    return null;
}

$url = 'http://blog.example.com/path/to/resource';
$secondLevelDomain = getSecondLevelDomain($url);
echo "二级域名是: " . $secondLevelDomain; // 输出: blog
?>

$url = 'http://blog.example.com:8080/path/to/resource';
$secondLevelDomain = getSecondLevelDomain($url);
echo "二级域名是: " . $secondLevelDomain; // 输出: blog

function getSecondLevelDomain($url) {
    $parsedUrl = parse_url($url);
    $host = $parsedUrl['host'];
    
    // 分割主机名以获取二级域名
    $domainParts = explode('.', $host);
    
    // 假设顶级域名至少有一个部分
    if (count($domainParts) > 2) {
        $secondLevelDomain = $domainParts[count($domainParts) - (count($domainParts) - 2)];
        return $secondLevelDomain;
    }
    
    return null;
}