正则表达式：当部分字符串失败时，整个字符串失败

Question

I've read through numerous posts on preg_match and can't find the answer. How to fail the whole preg_match when only one part of the haystack fails? I simply need to fail the whole preg_match, when the haystack ends with dot-anything (e.g., .html).

The groupings in here, before the problem area, are needed for other purposes and can't be changed. The portion I want to fail, when it contains a dot, is: ([^\.])* If that fails, the entire preg_match needs to fail. Note: the dot is only a "failing dot" if it occurs after the hyphen. There are dots before the hyphen that are not failing dots.

Everything on the right-hand side of the OR operator is fine. Nothing needs to be changed there.

preg_match('#^(.*)\/([0-9]+)\-([^\.])*|(.*)id_category=([0-9]+)(.*)$#', $haystack, $return_array)

Since I'm not evaluating the entire string for the dot, I have not been successful with negative lookahead. It only fails the one part, without failing the whole preg_match.

Answer 1

You can add any such condition as a (negative) lookhead at the start of the regex.

preg_match('#^(?!.*\..+$)((.*)\/([0-9]+)\-([^\.])*|(.*)id_category=([0-9]+)(.*)$)#', $haystack, $return_array)

Here it would fail when there is a '.' with at least one character afterwards. But if you are looking for fileendings, you can e.g. limit the amount of following characters:

(?!.*\..{1,4}$)

See a simple example here in regex101