As I'm using PCRE in PHP every now and then I find it pretty easy to come up with a pattern when I now WHAT to match. But the other way round... when it comes to patterns or pattern parts that need to describe what NOT to match... this really gives me headaches sometimes...

So starting with a basic thing: what is the simplest pcre pattern that matches any whole string but only if that string does not contain "foobar"?

This regex will do just that:

^((?!foobar).)*$

OK, using assertions, thank you!

So i guess this is equivalent:

^(.(?<!foobar))*$

schnizZzla:

OK, using assertions, thank you!

So i guess this is equivalent:

^(.(?<!foobar))*$

Correct.

And you're welcome!