(from Python check for valid email address?)
I don't completely understand
[^@]+@[^@]+\.[^@]+
Can someone explain this in detail?
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Type in your regex at http://rick.measham.id.au/paste/explain.pl and see for yourself. Voting to close. – devnull Apr 17 '14 at 02:03
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This answer from the [Stack Overflow Regular Expressions FAQ](http://stackoverflow.com/a/22944075/2736496) may also be of interest: [validating email addresses](http://stackoverflow.com/questions/201323/using-a-regular-expression-to-validate-an-email-address) as listed under "Common Validation Tasks] – aliteralmind Apr 17 '14 at 02:11
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It looks for 1+ non-@ characters, followed by an @, followed by 1+ non-@ characters, followed by a ., followed by 1+ non-@ characters.
[]s denote a character class, and the ^ negates the character class. + matches 1+ of the preceding characters. Finally, the . is escaped like \. because the . is a reserved symbol meaning "any character".
This means it isn't the best method for checking emails, since there are a lot more restrictions. For example, this would validate a 10,000 character long email or an email with a domain like !@#.com.
Get used to using a tool like Regex101 for testing expressions and getting good descriptions.
Sam
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[^@]+ - checks for anything that is not the @ symbol, one or more times.
@ searches for the @ symbol, clearly.
\. searches for the . character (it must be escaped since . searches for any character)
So it looks for any string not containing @, followed by @, followed by any string not containing @, followed by ., followed by any string not containing @.
desired login
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A proper validator for the RFC822 address specification (section "6. ADDRESS SPECIFICATION" on page 27) is a bit more complex than a small regex.
In order to do this properly, a grammar would be needed(like the one described in said rfc) but a regex works too. Such a regex can be found in the Email::Valid module, more exactly right here. I haven't tried that regex in Python(but it works fine in Perl).
AFAIK that's the de facto way of checking if an e-mail address is rfc822-valid. Also see this SO post for more details.
But to answer your question now, the regex [^@]+@[^@]+\.[^@]+ reads as "At least one or more non-@ , then a @ , then at least one or more non-@ , then a dot, then at least one or more non-@".
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The de facto way of determining if an e-mail address is valid is *sending an e-mail*. If it bounces or the mailer reports an error, it's invalid. – ashastral Apr 17 '14 at 02:27
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I think there's a misunderstanding, I meant valid as in rfc822-valid (as can be read above^^) – wsdookadr Apr 17 '14 at 02:29
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