PHP获取网站域名跟地址的代码

	function PMA_getenv($var_name) {		if (isset ( $_SERVER [$var_name] )) {			return $_SERVER [$var_name];		} elseif (isset ( $_ENV [$var_name] )) {			return $_ENV [$var_name];		} elseif (getenv ( $var_name )) {			return getenv ( $var_name );		} elseif (function_exists ( 'apache_getenv' ) && apache_getenv ( $var_name, true )) {			return apache_getenv ( $var_name, true );		}		return '';	}	if (empty ( $HTTP_HOST )) {		if (PMA_getenv ( 'HTTP_HOST' )) {			$HTTP_HOST = PMA_getenv ( 'HTTP_HOST' );		} else {			$HTTP_HOST = '';		}	}	//echo htmlspecialchars($HTTP_HOST );