Question

Im working on a commenting web application and i want to parse user mentions (@user) as links. Here is what I have so far:

$text = "@user is not @user1 but @user3 is @user4";

$pattern = "/\@(\w+)/";
preg_match_all($pattern,$text,$matches);

if($matches){   

    $sql = "SELECT * 
            FROM users 
            WHERE username IN ('" .implode("','",$matches[1]). "')
            ORDER BY LENGTH(username) DESC";
    $users = $this->getQuery($sql);

    foreach($users as $i=>$u){
        $text = str_replace("@{$u['username']}",
        "<a href='#' class='ct-userLink' rel='{$u['user_id']}'>@{$u['username']}</a> ", $text);
    }

    $echo $text;
}

The problem is that user links are being overlapped:

<a rel="11327" class="ct-userLink" href="#">
    <a rel="21327" class="ct-userLink" href="#">@user</a>1
</a>

How can I avoid links overlapping?

Answer Update

Thanks to the answer picked, this is how my new foreach loop looks like:

foreach($users as $i=>$u){
    $text = preg_replace("/@".$u['username']."\b/",
    "<a href='#' title='{$u['user_id']}'>@{$u['username']}</a> ", $text);
}

Answer 1

Problem seems to be that some usernames can encompass other usernames. So you replace user1 properly with <a>user1</a>. Then, user matches and replaces with <a><a>user</a>1</a>. My suggestion is to change your string replace to a regex with a word boundary, \b, that is required after the username.