regex-negation

The following are pseudo examples, not real regex, but still an example of what I mean: .* (anything) -.* (NOT anything) [A-Z] (Any letter A to Z, caps only) -[A-Z] (NOT any letter A to Z, caps only) EDIT: Changed inverse into complement in the question. Here's where the change was made: "turn any regex into an complement of itself " First of all, I believe you mean the complement of a regular expression, not it's inverse. The inverse of a regular expression doesn't make much sense; but if viewed as a function, I suppose you could say that the inverse of the matcher is the generator which

I need a single-pass regex for unix grep that contains, say alpha, but does not contain beta. grep 'alpha' <> | grep -v 'beta' ^((?!beta).)*alpha((?!beta).)*$ would do the trick I think. The other answers here show some ways you can contort different varieties of regex to do this, although I think it does turn out that the answer is, in general, “don’t do that”. Such regular expressions are much harder to read and probably slower to execute than just combining two regular expressions using the boolean logic of whatever language you are using. If you’re using the grep command at a unix shell

I'm trying to write a regular expression to match anything that isn't "foo" and "bar". I found how to match anything but one word at Regular expression to match a line that doesn't contain a word? but I'm not very skilled with regex and am unsure of how to add a second word to this critera. Any help would be most appreciated! CLARIFICATION: I wanted to match on anything that wasn't EXACTLY foo or bar. Tim Pietzcker Answer to the question: "A Regular Expression to match anything that isn't "foo" and "bar"?" ^(?!foo$|bar$).* would do exactly that. ^ # Start of string (?! # Assert that it's

How would I write a regular expression that matches the following criteria? No numbers No special characters No spaces in a string The caret inside of a character class [^ ] is the negation operator common to most regular expression implementations (Perl, .NET, Ruby, Javascript, etc). So I'd do it like this: [^\W\s\d] ^ - Matches anything NOT in the character class \W - matches non-word characters (a word character would be defined as a-z, A-Z, 0-9, and underscore). \s - matches whitespace (space, tab, carriage return, line feed) \d - matches 0-9 Or you can take another approach by simply

quick question: my pattern is an svg string and it looks like l 5 0 l 0 10 l -5 0 l 0 -10 To do some unittest comparison against a reference I need to ditch all but the first l I know i can ditch them all and put an 'l' upfront, or I can use substrings. But I'm wondering is there a javascript regexp idiom for this? You can try a negative lookahead, avoiding the start of the string: /(?!^)l/g See if online: jsfiddle Rob W There's no JS RegExp to replace everything-but-the-first-pattern-match. You can, however, implement this behaviour by passing a function as a second argument to the replace

For PMD I'd like to have a rule which warns me of those ugly variables which start with my. This means I have to accept all variables which do NOT start with my. So, I need a RegEx (re) which behaves as follows: re.match('myVar') == false re.match('manager') == true re.match('thisIsMyVar') == true re.match('myOtherVar') == false re.match('stuff') == true I've tried different ones (will list them here later, sorry, no access to them right now) but haven't got it working yet. You could either use a lookahead assertion like others have suggested. Or, if you just want to use basic regular