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Comment by Rainymood | Hacker News Reader

Author here. I actually did not know this. I used this very old book (Unix Power Tools) and after finishing the chapter on regex I didn't recall seeing a `+` operator (maybe I forgot to add it or skipped over it). But indeed the `+` operator seems to make significantly more sense here.

Thanks!

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No problem =) I was just a bit confused myself as I saw that pattern an it didn't instantly make sense why someone would write that. If you often use regex like I do. You kinda instantly see that something is weird if pattern have repeating sub pattern. It basically should never happen if the pattern is simplified.

You may wanna have a look at the PCRE flavor if you understand this you can work with all others (you'll only gonna miss some features)

The + is really just a shortcut for {1,} means 1 or more greedy the * is a shortcut for {0,} means 0 or more greedy Also while I'm at it the "even more correct" pattern ofc would be \d+ (at least in PCRE) \d stand for digit it shortcut for [0-9] Personally I would never write [0-9] I only ever use sets for partial ranges i.e. [5-9] or [a-f] Whenever you need the "full" set there is usually a short way to write it. This makes pattern shorter and easier to read. Another nice trick is to uppercase the shortcuts to invert it's meaning so \D would match any non-digit.

'+' isn't a part of BRE syntax. It stems from ERE and all of its offshoots.

https://www.gnu.org/software/sed/manual/html_node/BRE-syntax...

The "+" only saves you a few keystrokes. Using "*" is also fine and not wrong, but a little more error prone, so I would note to better use "+" in a peer review.

Exactly, it mostly about readability which is often (not always) better if the shortest possible pattern is used.

[0|1|2|3|4|5|6|7|8|9][0|1|2|3|4|5|6|7|8|9]{0,} and [0-9][0-9]* and [0-9]+ and \d+ all do the same so they are not wrong as in the result will be correct.

Genuine question. Why would you write a guide for 'noobs', when you don't know the basics yourself? It seems kind of silly.

I seem to have deleted part of the title. The article is titled

>Regex For Noobs (like me!) - an illustrated guide

So I am painfully aware that I'm a noob too, I even call myself one! I wrote this little piece because I felt that regex can be kind of intimidating for a lot of people but that it's actually pretty OK and fun once you get the hang of it. To get people over that initial barrier is what I aim to do with the "guide".

Because noobs wouldn't know to find problems ;)

It's a great way to reinforce your own learning, share what you just learned, and get great feedback (many of the comments in this thread)

People who are new to a topic and just learned a new thing often do a better job at explaining things without requiring prior knowledge. Experts in a topic often see things as trivial and write introductions that exclude a fraction of potential readers that lack a skill.

I can recommend the articles by Julia Evans[1], which are pretty much like this. She works on a problem that is new to her and describes how she solved it or how she learned something new.

[1]: https://jvns.ca/

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