I wanted to append a prefix to the beginning of the contents of a bunch of cells in #LibreOffice Calc, and the "simplest" way I found to do that today (from what I saw as recommendations in forums like StackOverflow and Reddit)… was to use regexes

So, to prefix the contents, I searched for:
^(.)

…and replaced by:
The string you want to add as a prefix $1

I feel dirty.

I have written regular expression engines, in multiple languages and with various performance guarantees. I have written multiple peer-reviewed academic papers on regular expressions, and presented at multiple conferences on them. I was invited to lecture on regex transformations for multiple three-letter agencies.

Anyway yeah any time I write a regex I fuck it up.

#Python and #RegularExpressions are fun. Trying to map one set of unique identifiers against another, on a dataset that has discernable patterns but too much variability to do a simple Excel formula. Sometimes there are spaces, sometimes it's one to many. Also, the boss keeps tweaking his ask. Since it's working it a) makes it look like I know what I'm doing and b) is essentially getting to do puzzles on the clock. My opinion will, of course, change if it stops working.

Just had to rename a bunch of files underscore-separated timestamps, and did a Python gist to facilitate this task to myself in the future.

https://gist.github.com/juandesant/16c337e15a87f430c3ab8483ffa0506d

New at PragProg

Staffan Nöteberg helps you really understand how the machinery works under the hood. Learn advanced tools like reluctant, lookbehind and nondeterministic finite automata to write efficient and elegant regexes with ease.

In this illustrated guide, you gain precisely that understanding., even with no prior knowledge of Regular Expressions.

http://pragprog.com/titles/d-snrem

@staffannoteberg

At a past position, the team I was on had a #regex that was several kilobytes in length in several products. It was the stuff of nightmares! We only managed by splitting their definition strings into multiple pieces that were assembled kind of like a puzzle.

That said, it was also an amazing learning experience and taught me about things to be extremely careful about, like don’t go too deep with the nesting of groups, and definitely don’t sprinkle deeply nested groups with the Kleene star or anything else that is unbound in length or repetition.

(I still love #RegularExpressions for their power, though. )

Struggling with text manipulation in Linux? My new article at https://www.spsanderson.com/steveondata/posts/2025-01-10/ breaks down Regular Expressions into easy-to-understand concepts! Perfect for beginners looking to enhance their skills.

#Blog #RegEx #regularexpressions #Programming #Linux #code

Share your thoughts in the comments!

Regular (Expression) Chess - [Nicholas Carlini] found some extra time on his hands over the holiday, so he deci... - https://hackaday.com/2025/01/07/regular-expression-chess/ #regularexpressions #softwarehacks #games #chess #cpu

Ways of identifying prime numbers:
Sieve of Eratosthenes
Euclid's Algorithm
#RegularExpressions?!

https://youtu.be/5vbk0TwkokM?si=eLVVVn5fpu1CKeKk

@drq: Сегодняшние регулярки будут очень короткими.

@skobkin:

Sometimes, I wish #regularExpressions supported modifiers/functions, for example to flip the case of a captured group of text. And then I remember that they're probably complex enough already.

Regular Expressions Finally Come to Microsoft Excel - There are two types of people in the world: those who have no idea what a regular ... - https://hackaday.com/2024/05/24/regular-expressions-finally-come-to-microsoft-excel/ #regularexpressions #softwarehacks #excel #regex

Regular expressions are one of the concepts that are almost universally used. Knowing, at least on a basic level, is also one of the core skills. Fanboys use regex101.com to check the matching/non-matching conditions and pros play with regexcrossword.com in the free time. But did you know that one might get into trouble if not careful when writing a regex?

If we allow untrusted user input, we could be dealing with a Denial-of-Service attack . It can happen, if we do not prevent that, for example, by setting a timeout for how long the regular expression engine should process our data.

Especially problematic are inputs that almost match the provided patterns. If our regex relies on backtracking and the input almost matches, the engine might need to spend too much time trying to match that string and never succeed. It will see that more and more characters are matching but at the very end a non-matching one would occur causing the engine to return to previous state and try to pick a different matching route.

See the example code from the linked page below

Docs : https://learn.microsoft.com/en-us/dotnet/standard/base-types/best-practices-regex

#dotnet #regex #regularexpressions
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If you find this useful, consider giving a like & share

I just published “Hugo Regular Expressions (featuring ignoreFiles)” at
https://www.ii.com/hugo-regular-expressions-ignorefiles/
#InfiniteInk #GoHugo #Hugo #ignoreFiles #RE2 #RegEx #RegExp #RegularExpression #RegularExpressions #ReplaceRE #Tech #Byℵ #ByNM

Сегодня опять буду делать пиратский стрим регулярок. Точнее того куска, где буду я

Searching code can be a challenge! In this post, @docs_guy shows how to use grep for search.

Find out how this developer essential can boost productivity and help you use other languages and tools with #RegularExpressions

https://developer.mozilla.org/en-US/blog/searching-code-with-grep/
#MDNBlogUpdate

#mozdevnet
Original tweet: https://twitter.com/MozDevNet/status/1683844688015499264 25 Jul 2023 16:20 CEST

Any #RakuLang core hackers want to take up this challenge?

#RegularExpressions #RegExps #RegExes #RegEx https://ruby.social/@gd/110718818730295923