Question

If this script detects then displays all # tags, how do i change it so it makes them all a hyper link? Basically putting an <a href="#">infront of it and a </a> behind

$str = <<<STR
this is a string
with a #tag and
another #hello one
STR;

$matches = array();
if (preg_match_all('/#([^\s]+)/', $str, $matches)) {
  var_dump($matches[1]);
}

Answer 1

You can use back-references, and preg_replace to do this.

echo preg_replace('/#([^\s]+)/', '<a href="#">$1</a>', $str);

Output:

this is a string
with a <a href="#">tag</a> and
another <a href="#">hello</a> one

If you want the # to be part of the link, simply change the regex to /(#[^\s]+)/.

Demo: http://ideone.com/T06HQ