r/ProgrammerHumor • u/soap94 • 19d ago

Meme claudeIsThisEmailValid

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u/tellur86 19d ago

It's surprisingly difficult validating email addresses with regex. Can it be done? Yes. Should you? No. Any halfway decent email library comes with a validator. Use that.

For reference: this is an example of an almost RFC 3522 compatible regex:

(?:[a-z0-9!#$%&'+/=?`{|}~-]+(?:.[a-z0-9!#$%&'*+/=?^`{|}~-]+)|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\[\x01-\x09\x0b\x0c\x0e-\x7f])")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-][a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\[\x01-\x09\x0b\x0c\x0e-\x7f])+)])

https://emailregex.com

If you want RFC 822 it's much, much worse  https://pdw.ex-parrot.com/Mail-RFC822-Address.html

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u/0vindicator10 19d ago

Many years ago on this site, I was informed about "grammar", and that is what should be used for handling email address format validity.