I was trawling through the PHP function reference the other day, looking for some information on regular expressions, when I happened across this gem:
$text = ereg_replace("[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/]", "<a href=\"\\0\" rel=\"nofollow\">\\0</a>", $text);
It may look like gibberish at first, but if you look at it for awhile, you might be able to guess what it does.
Suppose you’re writing a PHP script that displays data, let’s use blog comments as an example. Sometimes the data being displayed may have a URL pasted into it by the user that submitted it. Wouldn’t it be nicer for the end user if URLs like that were automatically turned into clickable links, so “http://google.com” would become “http://google.com?”
That’s exactly what this line of PHP code does. It takes the variable
$text and parses through it, converting stray URLs into clickable links.