I'm trying to use `preg_replace()` to remove all hexadecimal characters in a string (with only lower case letters):

```
$line = "sjdivfriyaaqa\xd2vkmpcuyyuen";
$line = preg_replace('/\\x[0-9a-f]{2}/', '', $line);
echo($line);

```

This should, as I understand it, echo `sjdivfriyaaqavkmpcuyyuen` (`$line` with `\xd2` removed) but it echoes the original `$line`. Why?