<?php // http://stackoverflow.com/q/33180712/5290909
// Replace URLs inside <pre> tags
$postbits = "
<pre>
http://www.google.com
http://w...content-available-to-author-only...o.com
http://www.microsoft.com/ <-- only this one clickable
</pre>";
$regex = '#\G((?:(?!\A)|.*<pre)(?:(?!</pre>).)*)(https?://\S+?)#isU';
$repl = '\1<a href="\2" target="_blank">\2</a>';
echo $postbits;
?>
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