php正则表达式匹配URL中的域名

3. $search = '~^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?~i';

4. $url = 'http://www.php.com/pub/ietf/uri/#Related';
5. $url = trim($url);
6. preg_match_all($search, $url ,$rr);
7. printf("

   输出URL数据为：

   %s

   \n",var_export( $rr ,TRUE));

8. /*

9. 各分组如下
10. $1 = http:
11. $2 = http
12. $3 = //www.php.com
13. $4 = www.php.com
14. $5 = /pub/ietf/uri/
15. $6 =
16. $7 =
17. $8 = #Related
18. $9 = Related
19. */
20. ?>

这里提供另一个简洁的代码：

2. // 从 URL 中取得主机名
3. preg_match("/^(http:\/\/)?([^\/]+)/i", "http：//www.php.com/index.html", $matches);
4. $host = $matches[2];
5. // 从主机名中取得后面两段
6. preg_match("/[^\.\/]+\.[^\.\/]+$/", $host, $matches);
7. echo "domain name is: {$matches[0]}\n";
8. ?>

执行后输出：domain name is: php.com