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What does the regular expression "[^\s@]+@[^\s@]+\.[^\s@]+" actually do?

Posted on 2014-01-13
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I'm trying to find a regex for email validation and someone suggested

[^\s@]+@[^\s@]+\.[^\s@]+

but looking up what the expression means here:

http://www.cheatography.com/davechild/cheat-sheets/regular-expressions/

It seems to be expecting lots of white space which doesn't make any sense.

Testing the expression it does seem fine for validating email addresses btw - I just can't understand how it is doing it.
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Question by:purplesoup
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Guy Hengel [angelIII / a3] earned 1600 total points
ID: 39776215
the ^ in the front of the \s@ part means NOT.
so, the expression above sais:

must start and have at least 1 non-space and non-@ character
then 1 @
continue and have at least 1 non-space and non-@ character
then 1 .
end and have at least 1 non-space and non-@ character
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Assisted Solution

by:ozo
ozo earned 400 total points
ID: 39776245
perl -MYAPE::Regex::Explain -e "print YAPE::Regex::Explain->new(qr/[^\s@]+@[^\s@]+\.[^\s@]+/)->explain"
The regular expression:

(?-imsx:[^\s@]+@[^\s@]+\.[^\s@]+)

matches as follows:
 
NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  [^\s@]+                  any character except: whitespace (\n, \r,
                           \t, \f, and " "), '@' (1 or more times
                           (matching the most amount possible))
----------------------------------------------------------------------
  @                        '@'
----------------------------------------------------------------------
  [^\s@]+                  any character except: whitespace (\n, \r,
                           \t, \f, and " "), '@' (1 or more times
                           (matching the most amount possible))
----------------------------------------------------------------------
  \.                       '.'
----------------------------------------------------------------------
  [^\s@]+                  any character except: whitespace (\n, \r,
                           \t, \f, and " "), '@' (1 or more times
                           (matching the most amount possible))
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
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