Auto link function not working properly

Question

I created a PHP function that will automatically turn URLs into links, link Twitter @reply usernames to its Twitter profile, and turn email addresses into links with the mailto protocol.

Here is the script:

function autolink($a, $b){
        $e = "";
        $f = array(
            'link' => '~(http(s|)\:\/\/(www\.|)((\w+)\.(\w+)(\:[0-9]{2,5}|)\.[a-z]{2,5}|(\w+)(\:[0-9]{2,5}|)\.[a-z]{2,5}))((((\/|)\w+)(\.[a-z]{2,5}|))+)(\?(\w+\=\w+(\&|))+|)~',
            'email' => '~\w+\@\w+(\:[0-9]{2,5}|)\.[a-z]{2,5}~',
            'twitter' => '~\@([a-zA-Z_0-9]){1,15}~'
        );
    switch ($b) {
    case "link":$e = preg_replace_callback($f['link'], function ($a) {return '<a href="'.$a.'" rel="nofollow" target="_blank">'.$a.'</a>';},$a);break;
    case "email":$e = preg_replace_callback($f['email'], function ($a) {return '<a href="mailto:'.$a.'" rel="nofollow" target="_blank">'.$a.'</a>';},$a);break;
    case "twitter":$e = preg_replace_callback($f['twitter'], function ($a) {return '<a href="https://twitter.com/#!/'.str_replace('@','',$a).'" rel="nofollow" target="_blank">'.$a.'</a>';},$a);break;
    }
    return $e;
}

The only issue I'm having is that instead of returning the link it returns the word: "Array".

For example, this:

autolink("This is my site http://weebuild.biz", "link");

Is returning this:

This is my site Array

When it should be returning this:

This is my site <a href="http://weebuild.biz" rel="nofollow" target="_blank">http://weebuild.biz</a>

The original script was in JavaSript which I wrote as well: http://jsfiddle.net/shawn31313/umgqR/2/

Since I'm not a PHP developer the JavaScript version has some more features.

Maybe the issue is that I took the regular expression from JavaScript and just put it in the PHP. I'm not sure if regular expressions in PHP are different from JavaScript.

Thanks in advance.

Answer 1

Try the following change:

case "link":$e = preg_replace_callback(
        $f['link'],
        function ($a) {
            return '<a href="'.$a[0].'" rel="nofollow" target="_blank">'.$a[0].'</a>';
        },
        $a
     );
     break;

The issue is that the argument to the callback will be an array, not a string.

From the docs:

A callback that will be called and passed an array of matched elements in the subject string. The callback should return the replacement string.

Answer 2

The $a inside of the callback is an array and returns something like this:

Array
(
  [0] => http://weebuild.biz
  [1] => http://weebuild.bi
  [2] => 
  [3] => 
  [4] => weebuild.bi
  [5] => 
  [6] => 
  [7] => 
  [8] => weebuild
  [9] => 
  [10] => z
  [11] => z
  [12] => z
  [13] => 
  [14] => 
  [15] => 

)

You might want to refer to $a[0] instead of just $a. Of course you need to do some checks to make sure there's that value and avoid any unexpected errors when referring to it.