Oct 15, 2009 · What is the literal meaning of this regex that contains a lookahead? 52. Reference - What does this regex ...

That looks like a typical password validation regex, except it has couple of errors. First, the .* at the beginning doesn't belong there. If any of those lookaheads doesn't succeed at the beginning of the string, there's no point applying them again at the next position, or the next, etc..

Why are you using pattern matching when all you need is an exact string comparison against a set of legal strings? Unless your regex compiler optimizes alternatives into an O(1) trie structure the way Perl’s does, you should probably be doing a test against hash membership instead. Other regex engines just aren’t very clever at this. –

May 15, 2010 · What does \\d+ mean in a regular expression?

I searched a lot, but nowhere is it written how to remove non-ASCII characters from Notepad++. I need to know what command to write in find and replace (with picture it would be great). If I want to

Be aware that the first ^ in this answer gives the regex a completely different meaning: It makes the regular expression look only for matches starting from the beginning of the string. In this case, that would effectively be a no-op if you run the regular expression only once. If you want to look for multiple matches within a single string ...

Aug 3, 2017 · In regex in general, ^ is negation only at the beginning of a character class. Unless CMake is doing something really funky (to the point where calling their pattern matching language "regex" could be regarded as misleading or incorrect) I'm guessing the fact that it worked for you was an isolated accident.

@Lupos \s is regex for “whitespace”. To code a literal backslash in Java, you must escape the backslash with another backslash, so to code \s in the regex, you must code "\\s" in your program. – Bohemian ♦

On greedy vs non-greedy. Repetition in regex by default is greedy: they try to match as many reps as possible, and when this doesn't work and they have to backtrack, they try to match one fewer rep at a time, until a match of the whole pattern is found.

Aug 18, 2010 · tl;dr non-capturing groups, as the name suggests are the parts of the regex that you do not want to be included in the capture and ?: is a way to define a group as being non-capturing. Let's say you have an email address [email protected]. The following regex will create two groups, the id part and @example.com part. (\p{Alpha}*[a-z])(@example ...