替换字符串中与php中的模式不匹配的所有URL

Question

I'm using this code to replace urls in a string

preg_replace('#<a.*?>(.*?)</a>#i', '\1', $text)

How do I do the same thing, but keeping urls that match a certain pattern (ie start with a domain I want to keep)?

Update

Turns out that the urls I want to keep include relative urls, so I now want to eliminate all urls that don't match the given url pattern and are not relative links.

Answer 1

You need a negative look-ahead assertion:

preg_replace('#<a(?![^>]+?href="?http://keepthisdomain.com/foo/bar"?).*?>(.*?)</a>#i', '\1', $text);

Edit: If you want to match only relative domains, the logic is the same. Just take out the protocol and domain name:

preg_replace('#<a(?![^>]+?href="?/?path/to/foo/bar"?).*?>(.*?)</a>#i', '\1', $text);

The ? after " and / means that those characters are optional. So, the second example will work for either path/to/foo/bar or /path/to/foo/bar .