Questions about replacing a preg_replace regular expression

About the replacement of a preg_replace regular expression in a recent Sina application, replace @ example with & lt; ahref = & quot; replace with a preg_replace regular expression.
Recently launched Sina application
Replace @ example with @ example

With the help of others, I wrote a regular expression.

PHP code

  $ T = preg_replace ("/* @ ([\ x {4e00}-\ x {9fa5} A-Za-z0-9 _] *)? /U "," @ \ 1 ", $ t );

It is found that if it is a normal Weibo nickname, it will be replaced with normal

However, once you encounter "@-example"

If there is a nickname "-", it will automatically add a space in front of "-" and become @-example

Excuse me, where is the problem?

Thank you ~ \ (Too many rows )/~ La la

------ Solution --------------------
([\ X {4e00}-\ x {9fa5} A-Za-z0-9 _] *)
This does not include-

Just add it.