Regex on Karpoke - Just Another Blog

How to Master Regex in Bash

Sun, 12 May 2024 09:21:39 +0100

regular expressions (regex), are perfect for matching, searching, and manipulating text based on specific patterns.

» unixmen.com | unixmen.com

Dos curiosidades sobre fórmulas relacionadas con los números primos

Sat, 19 Aug 2023 12:43:50 +0100

Esta regexp en Perl comprueba si un número es primo o no / Avinash Meetoo En los últimos meses descubrí un par de curiosidades sobre fórmulas para generar números primos y comprobarlos, entendiendo por «fórmulas» o bien una función matemática o bien…

» @Alvy | microsiervos.com

URL RegEx Pattern – How to Write a Regular Expression for a URL

Tue, 16 May 2023 00:09:56 +0100

Regular expressions provide a powerful and flexible way to define patterns and match specific strings, be it usernames, passwords, phone numbers, or even URLs. In this article, I’ll show you the fundamentals of crafting a regular expression for URLs….

» freeCodeCamp.org | freecodecamp.org

What Does '$' Mean in RegEx?

Sat, 22 Apr 2023 12:02:40 +0100

The $ symbol is one of the most commonly used symbols in RegEx. It is used to match the end of a string. In other words, you can call it “end of line anchor”, since it anchors a pattern to the end of the line. In this article, I’ll show

» freeCodeCamp.org | freecodecamp.org

Use ChatGPT to Build a Low Code RegEx Generator

Fri, 31 Mar 2023 21:37:28 +0100

Are you tired of spending hours writing complex Regular Expressions (RegEx) to manipulate strings? Do you want to learn how to build a RegEx generator quickly and easily? Then this course is for you! We just published a course on the freeCodeCamp.org…

» freeCodeCamp.org | freecodecamp.org

My Top 3 Regex Tools

Mon, 26 Dec 2022 12:24:19 +0100

A regular expression - short regex - is a sequence of characters that defines a search pattern.

» hackernoon.com | hackernoon.com

Diving Deeper in Vim Regular Expressions

Wed, 30 Nov 2022 18:14:51 +0100

Let

» The Valuable Dev | thevaluable.dev

The Regular Expression (RegEx) Cheat Sheet you always wanted

Fri, 19 Aug 2022 22:07:35 +0100

I get it even though Regex is incredibly useful, it is extremely hard to master! This is a cheat…

» DEV Community | dev.to

Una recopilación de las funciones RegEx más habituales

Sun, 27 Feb 2022 15:03:00 +0100

RegEx Library es una recopilación de la gente de UI Bakery en la que se pueden encontrar las expresiones regulares (RegEx) más comunes, incluyendo las que se suelen usar para la validación y extracción de datos de: Direcciones de correo Números…

» @Alvy | microsiervos.com

Comando Sed, con ejemplos para reemplazar textos y cadenas en Linux

Tue, 06 Jul 2021 10:37:21 +0100

En mi artículo anterior sobre las expresiones regulares, di algunos ejemplos de maneras en las que sepuede utilizar en la línea de comandos, con varias utilidades. Las Expresiones regulares también se pueden utilizar dentro de muchos editores de texto (a veces con una sintaxis…

» Javier Orovengua | linuxparty.es

Regular Expressions cheat sheet

Thu, 03 Dec 2020 16:40:22 +0100

Regular expression is a powerful tool, and it can save lots of lines codes sometimes. What…

» DEV Community | dev.to

Intro to Bash Regular Expressions

Mon, 19 Oct 2020 23:55:39 +0100

To me, regular expressions are often made far more complicated than they need to be. Sure, there…

» DEV Community | dev.to

Regex para torpes

Mon, 27 Jul 2020 15:52:07 +0100

Regex para torpes

» blog.adrianistan.eu | blog.adrianistan.eu

Demystifying the regular expression that checks if a number is prime

Sat, 10 Sep 2016 18:02:00 +0100

A while back I was researching the most efficient way to check if a number is prime. This lead me to find the following piece of code:
public static boolean isPrime(int n) {
return !new String(new char[n]).matches(”.?|(..+?)\\1+”);
}
I was intrigued. While this might not be the most efficient way, it’s certainly one of the less obvious ones, so my curiosity kicked in. How on Earth could a match for the .?|(..+?)\1+ regular expression tell that a number is not prime (once it’s converted to its unary representation)?

Visualization of Regular Expression Character Classes

Tue, 26 Mar 2013 20:52:00 +0100

We all know the regular expression character classes, right? There are 12 standard classes:
[:alnum:] [:digit:] [:punct:]
[:alpha:] [:graph:] [:space:]
[:blank:] [:lower:] [:upper:]
[:cntrl:] [:print:] [:xdigit:]
But have you seen a visual representation of what these classes match? Probably not. Therefore I created a visualization that illustrates which part of the ASCII set each character class matches.

» Peteris Krumins | catonmat.net

Regular Expression Matching Can Be Simple And Fast

Thu, 21 Jun 2012 18:21:00 +0100

Historically, regular expressions are one of computer science’s shining examples of how using good theory leads to good programs. They were originally developed by theorists as a simple computational model, but Ken Thompson introduced them to programmers in his implementation of the text editor QED for CTSS. Dennis Ritchie followed suit in his own implementation of QED, for GE-TSS. Thompson and Ritchie would go on to create Unix, and they brought regular expressions with them. By the late 1970s, regular expressions were a key feature of the Unix landscape, in tools such as ed, sed, grep, egrep, awk, and lex.

Today, regular expressions have also become a shining example of how ignoring good theory leads to bad programs. The regular expression implementations used by today’s popular tools are significantly slower than the ones used in many of those thirty-year-old Unix tools.

This article reviews the good theory: regular expressions, finite automata, and a regular expression search algorithm invented by Ken Thompson in the mid-1960s. It also puts the theory into practice, describing a simple implementation of Thompson’s algorithm. That implementation, less than 400 lines of C, is the one that went head to head with Perl above. It outperforms the more complex real-world implementations used by Perl, Python, PCRE, and others. The article concludes with a discussion of how theory might yet be converted into practice in the real-world implementations.