Question: I know how to use preg\_match and preg\_match\_all to find the actual matches of regex patterns in a given string, but the function that I am writing not only needs the text of the matches, but to be able to traverse the string AROUND the matches...

Therefore, I need to know the position of the match in the string, based on a regex pattern.

I can't seem to find a function similar to strpos() that allows regex...any ideas?

Answer: 
You can use the flag [`PREG_OFFSET_CAPTURE`](http://php.net/manual/en/function.preg-match.php) for that:

```
preg_match('/bar/', 'Foobar', $matches, PREG_OFFSET_CAPTURE);
var_export($matches);

```

Result is:

```
array (
  0 => 
  array (
    0 => 'bar',
    1 => 3,     // <-- the string offset of the match
  ),
)

```

---

In a previous version, this answer included a capture group in the regular expression (`preg_match('/(bar)/', ...)`). As evident in the first few comments, this was confusing to some and has since been edited out by @Mikkel. Please ignore these comments.
preg\_match has an optional flag, `PREG_OFFSET_CAPTURE`, that records the string position of the match's occurence in the original 'haystack'. See the 'flags' section: <http://php.net/preg_match>