Show HN: RegEx for Regular Folk – A visual, example-based introduction

Post by bathory » Sat, May 02, 2020, 11:32 AM UTC

shreyasminocha wrote: post #46

nobrains wrote: post #43

Hi, very nice RegEx educational site/book. Feedback: - In the chapter https://refrf.shreyasminocha.me/chapters/character-classes an example is given which uses: o ^ character outside brackets o $ end of line o + But the explanation above does not introduce these yet, so a real beginner user (like me) is lost. The ambigious characters example is fine, since it uses all the concepts already explained.

Thanks. Yeah, others pointed this out too. I'll get to it soon!

Post by b3kart » Sat, May 02, 2020, 12:50 PM UTC

csunbird wrote: post #103

dntbnmpls wrote: post #94

Earlier quoted context omitted.

The biggest problem I've noticed for regex is we use it every once in a while and once it works we move onto other things. And a few weeks/months later, we have forgotten much of it and have to relearn it all over again. Whereas, you generally use your programming language ( C++, C#, Java, etc ) everyday to keep your skills sharp, regex is generally "set it and forget it" situation for most people. And as you noted,…

Please do not forget the fact that after a couple of months, you want to make a small change, but you forgot the edge cases when you first created the regex :D

Post by m463 » Sun, May 03, 2020, 1:00 AM UTC

7786655 wrote: post #85

m463 wrote: post #78

I think what regex's need is a really powerful syntax and language aware regex editor. I've been using regexs for most of my career, and still struggle to get them right on first writing. The #1 problem I run into is: what is a literal character and what is a control character? for example, both these are very common: - match a parenthesis character or a period character - use a parenthesis to group a match or use a…

I don't see the problem here. The regex itself is exactly the same, it's just that different languages have different string literal syntaxes (and some have dedicated regex syntax, thus solving the problem of double-escaping). The only regex engine where this is a problem is Vim's, because there are characters that a special unless escaped, and characters that are normal but become special when escaped . And as if th…

Post by m463 » Sun, May 03, 2020, 1:06 AM UTC

dntbnmpls wrote: post #94

m463 wrote: post #78

I think what regex's need is a really powerful syntax and language aware regex editor. I've been using regexs for most of my career, and still struggle to get them right on first writing. The #1 problem I run into is: what is a literal character and what is a control character? for example, both these are very common: - match a parenthesis character or a period character - use a parenthesis to group a match or use a…

The biggest problem I've noticed for regex is we use it every once in a while and once it works we move onto other things. And a few weeks/months later, we have forgotten much of it and have to relearn it all over again. Whereas, you generally use your programming language ( C++, C#, Java, etc ) everyday to keep your skills sharp, regex is generally "set it and forget it" situation for most people. And as you noted,…

Post by binstub » Sun, May 03, 2020, 1:29 AM UTC

bmn__ wrote: post #101

binstub wrote: post #59

Nice intro. Tangential question. Is there a regex tool that shows where the expression failed ? Not in syntax, but the logical failure point? Would be useful for when an expression gets a little long and nested and modifications need to be made. Edit: I mean like: Target text is abcde Regex is /abe/ Is there a tool that will tell me it matched a and b and then failed trying to match e ? Those sites are great resource…

You want a debugger. http://p3rl.org/rxrx rxrx -e'"abcde" =~ /abe/' Demo: https://blog-cloudflare-com-assets.storage.googleapis.com/20... http://p3rl.org/re#'debug'-mode perl -Mre=debug -e'"abcde" =~ /abe/' ---- https://stackoverflow.com/questions/2348694/how-do-you-debug...