php针对字符串的正则匹配

/** * is_external_link 检测字符串是否包含外链 * @param string $text 文字 * @param string $host 域名 * @return boolean false 有外链 true 无外链 * / function all_external_link($text = '', $host = '') { if (empty($host)) $host = $_SERVER['HTTP_HOST']; $reg = '/http(?:s?):\/\/((?:[A-za-z0-9-]+\.)+[A-za-z]{2,4})/'; preg_match_all($reg, $text, $data); $math = $data[1]; foreach ($math as $value) { if($value != $host) return false; } return true; }