PHP - Add link to a URL in a string

Question

I have a function that will add the tag before a link and after the link. However, it breaks for some webpages. How would

Answer 1

function processString($s){
  return preg_replace('@((https?://)?([-\w]+\.[-\w\.]+)+\w(:\d+)?(/([-\w/_\.]*(\?\S+)?)?)*)@', '<a href="$1">$1</a>', $s);
}

Found it here

Answer 2

function processString($s) {
    return preg_replace('/https?:\/\/[\w\-\.!~#?&=+\*\'"(),\/]+/','<a href="$0">$0</a>',$s);
}

Answer 3

It breaks for all URLs that contain "special" HTML characters. To be safe, pass the three string components through htmlspecialchars() before concatenating them together (unless you want to allow HTML outside the URL).