315
[xkcd] Regular Expressions (10 Jan 2007)
(programming.dev)
Hover Text:
Wait, forgot to escape a space. Wheeeeee[taptaptap]eeeeee!
Transcript
[in a yellow box:]
Whenever I learn a new skill I concoct elaborate fantasy scenarios where it lets me save the day.Megan: Oh no! The killer must have followed her on vacation!
[Megan points to computer.]
Megan: But to find them we'd have to search through 200 MB of emails looking for something formatted like an address!
Cueball: It's hopeless!Off-panel voice: Everybody stand back.
Off-panel voice: I know regular expressions.
[A man swings in on a rope, toward the computer.]
tap tap
The word PERL! appears in a bubble.[The man swings away, and the other characters cheer.]
Oh no
Who's gonna tell them? I'd do it but I'm still busy parsing HTML with regex.... it's working any minute now!
What am I missing? I typically used it as a sanity check and would vet the changes. Never as a one-click modify. Or is there something else I should know about?
This short article has some good examples at the top: https://sigparser.com/developers/email-parsing/regex-validate-email-address/
Basically, you can very easily make a regex to match 99% of email addresses, but technically an email could be something like "!@[124.35.6.72]"
Ah, yeah. It was never meant to be a be all and all. Just something to clean up the complete trash before I started proofreading. Besides, these were emails the customer provided and could easily be changed afterwords. Their fault if we get bad emails in the list ¯\_(ツ)_/¯
This is the way
You're completely correct. In practice, it's usually good enough to just check for ".+@.+" or ".+@.+\..+". Why? It's broad enough to allow almost everything and it rejects the most obvious typos. And in the end, the final verification would be to send an email there which contains a link, that one has to click to finalize the signup/change. Even if you had a regex that could filter every possible adress that's possible according to the standard, you still wouldn't know whether it really exists.
I wrote a regex that matches 100% of email addresses and had no problems using it. It's ".+@.+"
Meme aside that's what I'd use tbh. Or the ultimate email validation: just sending the signup email and if they typed an invalid email it won't send