Php to replace @username with link to twitter account

Question

I assume this is some to do with regex, but it\'s an art all it\'s own - and I need some help.

When we display a story, we store all the text in a varilable - let\'s

Answer 1

A positive lookbehind could do the trick:

preg_replace('/(?<=\s)@(.*?)/', '@$1')

going off the top of my head. "If there's a @ which is preceded by something which is whitespace, then take whatever follows after the @ and do the html tag wrapping".