parse-text-for-urls-script extended?

[jensos]

Hi!

I use the following regex to parse a text for urls. They will be changed into clickable urls.

$text = ereg_replace("[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/]","<a href=\"\\0\" target=_blank>\\0</a>", $text);

But how can I change the script, so that it will not affect existing hyperlinks (yet clickable urls) in the text?

Thanks in advance!

jens