如何将下面的 ereg 语句转换为 preg_replace
$message = ereg_replace("http://([.]?[a-zA-Z0-9_/-])*", "<a href=\"\\0\" target=\"_blank\">\\0</a>", $message);
$message = ereg_replace("(^| |\n)(www([.]?[a-zA-Z0-9_/-])*)", "\\1<a href=\"http://\\2\" target=\"_blank\">\\2</a>", $message);