Use substitution to replace every occurrence of the word i with the word I (uppercase, I as in me). E.g.: i'm replacing it. am i not? -> I'm replacing it. am I not?. A regex match is replaced with the text in the Substitution field when using substitution.

With regex you can count the number of matches. Can you make it return the number of uppercase consonants (B,C,D,F,..,X,Y,Z) in a given string? E.g.: it should return 3 with the text ABcDeFO!. Note: Only ASCII. We consider Y to be a consonant! Example: the regex /./g will return 3 when run against ...

Count the number of integers in a given string. Integers are, for example: 1, 2, 65, 2579, etc.

Find all occurrences of 4 or more whitespace characters in a row throughout the string.

Oh no! It seems my friends spilled beer all over my keyboard last night and my keys are super sticky now. Some of the time whennn I press a key, I get two duplicates. Can you ppplease help me fix thhhis? Substitute with $1

Validate an IPv4 address. The addresses are four numbered separated by three dots, and can only have a maximum value of 255 in either octet. Start by trying to validate 172.16.254.1.

Strip all HTML tags from a string. HTML tags are enclosed in . The regex will be applied on a line-by-line basis, meaning partial tags will need to be handled by the regex. Don't worry about opening or closing tags; we just want to get rid of them all. Note: This task is meant to be a learning exe...

Check if a floating point number (e.g. 3.14159) is in a valid format.

For every occurrence of the char #, match the previous character and save it in a group (backreference). Example: for the text "a#bc# -#", set backreferences with a, c and -. You are not allowed to consume the hash character.

Verify that a given e-mail address is valid. We all know how complex emails are, but despite this, let's give it a try and see what we can come up with. You could start by trying to match contact@regex101.com (denoted as @.).

This is a test

VALIDATING IP V4 1.1.1.1 2.2.2.2 3.3.3.3 4.4.4.4 5.5.5.5...

Replace every other character if it's a \d with * (only those in even positions: 2, 4, 6, etc). Example: a1b2cde3g45hi6 should become abcdeg4hi6

Use substitution to put commas in all numbers to separate the thousands. ie: 12345678 → 12,345,678. The number could be in a sentence, and there may be more than one number in the sentence.

Validate a line in quotes. Return one (and only one) backreference with the text. ie: quoted text from "quoted text". Note: a \ escapes any char, so \" is a valid escape.

In an HTML page, replace the text micro with µ. Oh, and don't screw up the code: don't replace inside or &entities;

Purpose: This is supposed to be a learning process. The first 1-9 tasks are supposed to be done with using "standard" regex, ie, teach the user to use \s, \w, \d, aswell as backrefs and similar basic things. Later down the road, at task 10-13 we start introducing them to lookarounds. These are fairl...

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Validación para fechas en formato ISO 8601 como 2024-12-13

Validación de fecha de formato europeo 13/12/2024