#26854 [Bgs]: Using ! as a delimiter for regexps will not allow neg. lookahead assertions

ID: 26854 User updated by: chris_se at gmx dot net Reported By: chris_se at gmx dot net Status: Bogus Bug Type: PCRE related Operating System: Linux PHP Version: 4.3.4 New Comment: Even if this is not a bug (in my eyes, it still is), it is at least a documentation problem: From http://www.php.net/manual/en/ref.pcre.php: ------------------------------------------------------ The syntax for patterns used in these functions closely resembles Perl. The expression should be enclosed in the delimiters, a forward slash (/), for example. Any character can be used for delimiter as long as it's not alphanumeric or backslash (\). If the delimiter character has to be used in the expression itself, it needs to be escaped by backslash. ------------------------------------------------------ From reading this text passage, it is perfectly valid to assume that what I have assumed. Previous Comments: ------------------------------------------------------------------------ [2004-01-09 12:57:59] andrei@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php Use a different delimiter instead. The library does not remove backslashes before delimiters and PCRE doesn't know what to do with (?\\!). ------------------------------------------------------------------------ [2004-01-09 12:39:04] chris_se at gmx dot net Description: ------------ When I try to use ! as delimiter and use a negative lookahead assertion which is normally started with (?!, (?! of course does not work, because the ! will terminate the pattern (and PHP will of course complain). But when I try to escape the exclamation mark like (?\!, an error occurs. I assume the \ is not removed in front of the ! after the pattern is freed from its delimiters. Reproduce code: --------------- $res = preg_match ("!^(?\\!foo)[a-z]{3}$!", "bar"); Expected result: ---------------- $res contains true Actual result: -------------- Warning: Compilation failed: unrecognized character after (? at offset 3 in /home/christian/- on line 2 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=26854&edit=1