Is it possible to preg replace unique variables into a string?

Question

What I want to do is use preg replace to replace matches within a string with a varying replacement, and I was wondering if anyone knew if that is possible in php or at least achievable by some means. For example, a string has two matches, then those matches will be replaced with two different variables. What I want are replacements to each be a unique id and I cannot figure out how this could possibly work or if php could even do this. For example if the match is 'a' and there is a sentence, 'put a smile on a person' then one 'a' will be unique id 98aksd00 and the other will be 09alkj08. I am retrieving my comments from a database so the preg replace is happening within

while ($row=mysql_fetch_assoc($query)){
//preg replace

If anyone could provide any insight into this, I would really appreciate it

Answer 1

You can use preg_replace_callback(), which will trigger a function call with every match:

$out = preg_replace_callback('!\bword\b!', 'replace_word', $in);

$id = 1;

function replace_word($matches) {
  global $id;
  return $id++;
}

Edit: to answer the question, this code snippet:

$message = preg_replace_callback("'\[test\](.*?)\[/test\]'",
  'replace_word' ,$message);

function replace_word() {
  return 'test';
}

The problem here is that you're using a double quoted string so you need to escape \. There's little reason to use double-quoted strings here. It also makes the syntax more confusing so:

$message = preg_replace_callback('!\[test\](.*?)\[/test\]!',
  'replace_word' ,$message);

function replace_word() {
  return 'test';
}