I have just noticed a problem running the regex "matches.php" and "pcre.php" pages in Chapter 13. The problem is probably present in all forms, not just the ones in this chapter, but I guess this the first time I started throwing escape characters into form fields.
Basically if I type "\" in the form element "pattern", I get "\\" in from $_POST['pattern']. Any and all escape characters get doubled. This obviously breaks the pattern matches in this chapter's examples, but could be a real pain down the road.
This doesn't seem to be browser specific, as it happens in Safari, Firefox and Chrome.
Setup information:
Mac OS 10.6
Development server is MAMP running PHP 5.3.5.
EDIT: Never mind, fixed it. Missing magic quotes pref in ini file.