What I'm trying to do: remove innermost unescaped square brackets surrounding a specific, unescaped character (\ is escape) input: [\[x\]]\]\[[\[y\]] output when looking for brackets around y: [\[x\]]\]\[\[y\] output when looking for brackets around x: \[x\]\]\[[\[y\]] In short, remove only the unescaped set of brackets around the spec...
Hello everyone! I have the following regexp: (?P<question>.+(?<!\[\[)) It is designed to match hello world! in the string hello world! [[A string typically used in programming examples]] Yet I just matches the whole string, and I can't figure out why. I've tried all flavors of lookaround, but it just won't work... Anyone knows how ...
Ive found these things in my regex buddy but i dont got a clue what for i can use them ? does somebody got some examples so i can try to understand how they work? (?!) - negative lookahead (?=) - positive lookahead (?<=) - positive lookbehind (?<!) - negative lookbehind (?>) - atomic group ...
There are some features in modern regex engines which allow you to match languages that couldn't be matched without that feature. For example the following regex using back references matches the language of all strings that consist of a word that repeats itself: (.+)\1. This language is not regular and can't be matched by a regex, which...
I have the following regex in a C# program, and have difficulties understanding it: (?<=#)[^#]+(?=#) I'll break it down to what I think I understood: (?<=#) a group, matching a hash. what's `?<=`? [^#]+ one or more non-hashes (used to achieve non-greediness) (?=#) another group, matching a hash. what's the `?=`? So the p...
i have strings in the form [abc].[some other string].[can.also.contain.periods].[our match] i now want to match the string "our match" (i.e. without the brackets), so i played around with lookarounds and whatnot. i now get the correct match, but i don't think this is a clean solution. (?<=\.?\[) starts with '[' or '.[' ([^\[]*) ...
As a personal learning exercise, I wrote this regex to split a unary string into parts whose length is increasing powers of two (see also on ideone.com): for (String s : new String(new char[500]) .split("(?=(.*))(?<=(?<=(^.*))\\G.*)(?<=(?=\\2\\2.\\1)^.*)") ) { System.out.printf("%s ", s.length()); } ...
This is the second part of a series of educational regex articles. It shows how lookaheads and nested references can be used to match the non-regular languge anbn. Nested references are first introduced in: How does this regex find triangular numbers? One of the archetypal non-regular languages is: L = { anbn: n > 0 } This i...
Here's a string that I may have: (MyStringIsOneWholeWord *) I have used the following javascript regular expression to get the text after the bracket if it starts with My. /(^|\s|\()+My(\w+)/g, The problem with this is that it includes the first bracket in the result, as that it is the letter/character that found it. How would I ...
This is the third part in a series of educational regex articles. It follows How does this regex find triangular numbers? (where nested references is first introduced) and How can we match a^n b^n with Java regex? (where the lookahead "counting" mechanism is further elaborated upon). This part introduces a specific form of nested as...
This is the fourth part in a series of educational regex articles. It show how the combination of nested reference (see: How does this regex find triangular numbers?) to "count" within assertions (see: How can we match a^n b^n with Java regex?) can be used to reverse a string. The programmatically generated pattern uses meta-pattern a...
Hello, everyone! I'm quite new to regular expressions, but I like them, A LOT! Call me nitpicky if you will, but I'd really like to know if I should avoid using lookaheads and lookbehinds if I have an option. For example, the two commands below do the same thing, one uses lookbehind and the other doesn't. the_str = Regex.Replace(the_s...