Can anyone explain this email validation regex
This regex is often used to validate email addresses:
Can anyone break it down and explain exactly what it is doing?
\w+([-+!$%&*/=?{|}.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*Can anyone break it down and explain exactly what it is doing?
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what part of this expression is not clear to you ? please explain
ASKER
I didn't understand what capturing groups were, as I think I mentioned, and the initial link I looked up didn't seem to explain it very well, however I did some more searching and I think I have the hang of it.
This is what I made of it:
([-+!$%&*/=?{|}.']\w+)*
The bits between ( and ) are the group. The * at the end refers to zero or more characters, if it had + on the end it would be one or more.
So now looking at the contents of the group, we have
[-+!$%&*/=?{|}.']\w+
Well the \w+ at the end is easy enough - a word character, one or more times.
So what of
[-+!$%&*/=?{|}.']
?
This I believe refers to any one of these characters is ok.
So valid matches might be
(nothing)
since the capturing group has * at the end, zero characters are a valid match.
+a
the plus (+) character is one of the allowed characters, but it has to be followed by at least one word character (in this case "a")
&abcd
the ampersand (&) character is one of the allowed characters, and it must be followed by one or more word characters, "abcd" is therefore acceptable.
This wouldn't be allowed:
%&*
because only one of the special characters is allowed and it isn't followed by one or more word characters.
That was the sort of explanation I was looking for.
This is what I made of it:
([-+!$%&*/=?{|}.']\w+)*
The bits between ( and ) are the group. The * at the end refers to zero or more characters, if it had + on the end it would be one or more.
So now looking at the contents of the group, we have
[-+!$%&*/=?{|}.']\w+
Well the \w+ at the end is easy enough - a word character, one or more times.
So what of
[-+!$%&*/=?{|}.']
?
This I believe refers to any one of these characters is ok.
So valid matches might be
(nothing)
since the capturing group has * at the end, zero characters are a valid match.
+a
the plus (+) character is one of the allowed characters, but it has to be followed by at least one word character (in this case "a")
&abcd
the ampersand (&) character is one of the allowed characters, and it must be followed by one or more word characters, "abcd" is therefore acceptable.
This wouldn't be allowed:
%&*
because only one of the special characters is allowed and it isn't followed by one or more word characters.
That was the sort of explanation I was looking for.
[-+!$%&*/=?{|}.'] -> one of these characters.
The link that posted , which is a reference to me also , explains/breaks every regular expresion .
If you feel that your are not satisfied with the answer , you can request the help of a moderator.
The link that posted , which is a reference to me also , explains/breaks every regular expresion .
If you feel that your are not satisfied with the answer , you can request the help of a moderator.
ASKER
http://www.regular-expressions.info/named.html
but I couldn't link it to what you had - can you make it any clearer for me?
Sorry!