I have been using following Regex to parse #username from posts in my application.
'/(^|\s)#(\w*[a-zA-Z_]+\w*)/
Can somebody explain me the purpose of (^|\s). What if I omit that part?
(^|\s) either matches the beginning of a string (^) or a space character (\s). This is in order to prevent hallo#world from matching as a mention.
An alternative to that is using \b (a word boundary). It has slightly different semantics, but it should work in this case.