Remove character during preg_replace function

I need to extract some text from a string, th开发者_如何学编程en replace that text with a character removed in one instance and not in another. Hopefully this example will show you what I mean (this is what I have so far):

$commentEntry = "@Bob1990 I think you are wrong...";
$commentText = preg_replace("/(@[^\s]+)/", "<a target=\"_blank\" href=\"http://www.youtube.com/comment_search?username=${1}$1\">$1</a>", $commentEntry);

I want the result to be:

<a href="http://www.youtube.com/comment_search?username=Bob1990">@Bob1990</a> I think you are wrong...

But am getting:

 <a href="http://www.youtube.com/comment_search?username=@Bob1990">@Bob1990</a> I think you are wrong...

I have been working on this one problem for at least an hour and nearly given up hope, so any help is greatly appreciated!

could try something like this

$commentText = preg_replace("/(@)([^\s]+)/", "<a target=\"_blank\" href=\"http://www.youtube.com/comment_search?username=$2\">$1$2</a>", $commentEntry);

What you can do is adapt the capturing. Move the @ out of the braces:

preg_replace("/@([^\s]+)/",

Then you can write your replacement string like

'<a href="...$1">@$1</a>'

Note how the first $1 just reinserts the text, and the second $1 is prefixed by a verbatim @ to get it back in.

You're capturing the @ in your pattern, so it'll always be output when you use $1. Try this instead:

$commentText = 
  preg_replace(
    "/@([^\s]+)/", 
    "<a target=\"_blank\" href=\"http://www.youtube.com/comment_search?username=$1\">@$1</a>", 
    $commentEntry
  );

The difference here is that the @ is no longer captured as part of $1 (i.e. it'll capture only Bob1990. Since it's a literal value, it doesn't need to be part of any pattern. Instead, I just changed it to output as a literal value in the element text, directly before the captured name. (i.e. it now does <a>@$1</a> rather than just <a>$1</a>).