I have this function, which color every @username contained in a string

```
 //color  @username
 function hashtag_links($string,$id_session) {
 preg_match_all('/@(\w+)/',$string,$matches);
 foreach ($matches[1] as $match) {
$string = str_replace("@$match", "<span class=color>@$match</span>", "$string");
 }
 return $string;
 }

```

Everything is good while the usernames are different (@cat,@pencil,@scubadiving), but in case the username starts with the same letters (@cat,@caterpiller,@cattering), the functions only colors the repeated letters in this case (@cat), what to do?