How can I use the negation within square brackets as an exception, to find e. g. everything between a-z except for the the range from m-o?
By the way: it’s not for the sake of this example that I ask, but to be able to exclude ranges within ranges, or even single letters within ranges. I am pretty much aware that in this example it can be calculated.
I use the Zend engine (PHP).
You should be able calculate the difference yourself.
If the regex engine supports lookahead assertion, you could use
but this would probably be less efficient.
In addition to what Kenny mentions: