搜索并替换URL-正则表达式？

Question

I'm trying to create a WordPress shortcode (the WordPress part of it isn't that relevant) that will search within some specified text for a link and replace it with one that I specify. For example:

[scode]Click on <a href="www.X.com">this link</a>[scode]
[scode]Click on <a href="www.Y.com">this link</a>[scode]

...will be changed to:

[scode]Click on <a href="www.Z.com">this link</a>[scode]

I'm trying to put together a function that will search for links and replace them with the one that I specify. Here's what I have right now:

// Adds [hide] shortcode for hiding content from non-registered users.

function hide_text( $atts,$content) {
    if ( is_user_logged_in () ) {
        return $content;
    }
    else {
        $pattern = '(?<=href=("|\'))[^"\']+(?=("|\'))';
        $newurl = "http://replacementurl.com";
        $content = preg_replace($pattern,$newurl,$content);
        echo $content;
          }
    }
add_shortcode( 'hide', 'hide_text' );

This just crashes the site, though. I'm not a PHP expert (much less an expert on regex), but are there at least any glaring irregularities in my code?

UPDATE:

I ran debug on the site and found out from the log that there was an extra } in there. Now the site isn't crashing, but the content being echoed is blank... Code updated above

Answer 1

http://replcaement url.com Pretty sure this is spelled incorrectly.

and there isn't an ; at the end of the line.

Looks like you've done the regex correctly for the most part you also need to escape some reserved characters look at @Akam's answer.

I suggest using preg quotes.

(?<=href=("|'))[^"']+(?=("|'))

Edit live on Debuggex

Answer 2

There is syntax error in your pattern, change it to:

    $pattern = "(?<=href=(\"|'))[^\"']+(?=(\"|'))";

Errors:

    $pattern = "(?<=href=("|'))[^"']+(?=("|'))";
                          ^--            ^--not escaped