Replace any ‘http://’ text URLs with clickable hyperlink that open in a new window:
<?php
function textToHyperlinks( $string ) {
return preg_replace(
'@(https?://([-\w\.]+[-\w])+(:\d+)?(/([\w/_\.#-]*(\?\S+)?[^\.\s])?)?)@',
'<a href="$1" target="_blank">$1</a>',
$string
);
}