RegEx Workout 001 - Introduction to Regex

KrzysztofNowak · May 15, 2023, 11:33am

Welcome to first Regex Workout.

The purpose of this exercise is to detect fragments of the given text that meet the requirements.

Our primary tool will be regex101.com. Let’s take a moment to get to know its interface:

The key elements of the tool are two windows. The smaller one is used to enter a regular expression. In the larger one you type the text you are analyzing.

On the right are the Explanation and Match Information panels. The first one tries to interpret our expression and the second one displays the identified elements.

Quick reference is knowledge base about regular expressions.

First challenge

Text to analyze:

“Thank you for paying the invoices INVOICE-2023123 and INVOICE-2021133, and we would also like to remind you to pay the invoices INVOICE-202023555 and INVOICE-20201455. We would also like to inform you that we are processing your credit note CR-202345345. We look forward to a successful cooperation in 2023.”

Tasks:

Level: Easy

Match first sign:

Match last sign:

Match all digits :

Level: Medium
Find all invoices:

Find all invoices but have the text part and special characters in one group and the numbers in a separate group.

Hard:

Match all financial documents, including “CR-XXX” . We will define them as every numeric value followed by uppercase string and “-“.

Submission

Simply post your code and a screenshot of your results.

Please format your Regex code and blur it or place it in a hidden section.

Solution to this challenge will be posted on May 21

borydobon · May 17, 2023, 8:20am

Medium+Hard

([A-Z]+)-(\d+)

BrianJ · May 19, 2023, 2:46am

@KrzysztofNowak ,

Terrific intro workout! I’d never used Regex101 previously, but it’s a great tool.

Already looking forward to Workout #2. Thanks!

Brian

EASY:

Summary

MEDIUM:

Summary

HARD:

Summary

KrzysztofNowak · May 21, 2023, 11:15am

Hello All, thank you for participation.

Below is my solution

Find first character. I decided to use “^” anchor which indicated start of line. Second value is “.” which means any character.

image908×546 88.6 KB
Find last character. I changed anchor from “^” to “$” and placed it after “.”. It means, look at the end of line.

image908×546 90.4 KB

3.Match all digits. In this case I use “\d” which means “digit”. We need "" as escape character. This way the tool knows that we do not mean the letter “d”.

4.Find all invoices. There is a few ways to complete this. Most direct is to mention “INVOICES-” and digits (one or more with “+”)

We could have more dynamic solution and say: At least 3 upper case letters(to avoid matching “CR”), non-word sign and digits (one or more).

In order to include “CR” in last question, change value in {} to 2

Regards

KrzysztofNowak · May 21, 2023, 11:17am

Good job, that You for submission @borydobon .

KrzysztofNowak · May 21, 2023, 11:21am

Hello @BrianJ , thank You for submission. All your answers are right. For last exercise
I decided to be a little more careful and avoid matching letter prefix shorter but 2, but results are the same.

alex-badiu · May 28, 2023, 1:36pm

A little late to the party, but here’s my workout solution!
Didn’t used Regex for 2 years. It was fun!

Level: Easy

Summary

Match first sign: ^.
Match last sign: .$
Match all digits: \d

Level: Medium & Hard

Summary

Find all invoices: (INVOICE).(\d+)
Match all financial documents, including “CR-XXX” : [A-Z]±\d+

BrianJ · May 28, 2023, 5:43pm

@KrzysztofNowak ,

Thanks! I’m really gaining an appreciation for the art and science of regex through these workouts.

It’s not just about getting the specific answer to the problem provided correct, but thinking about what else COULD go wrong with the data and proactively coming up with constructs that will successfully handle it.

Great stuff!