<?php $re = '~\B(?<!@)@([0-9a-z]+)(?:\s|$)~ui'; $str = "@ww@ee x@@vx @ss @aa assadd @sfsd";
Standard input is empty
Array
(
[0] => Array
(
[0] => @ss
[1] => @aa
[2] => @sfsd
)
[1] => Array
(
[0] => ss
[1] => aa
[2] => sfsd
)
)