I am using below regular expression in my application:
^([a-zA-Z0-9_\-\.&\*\+='/\{\}~]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$
But the limitation with this regex is that, it accepts dot(.) at the beginning, which is a wrong behaviour.
So can anyone please help me in updating this regex so that it should not accept (.) at its start.
I tried adding the suggested fregment "(?!\.)", but it didn't worked.
Could be the reason that I was not able to add it properly.
Could you please give me full regex?
Regards
Gaurav
Mike Simmons
Ranch Hand
Joined: Mar 05, 2008
Posts: 2770
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Well, that link you gave uses the Jakarta Regexp package, which is not exactly the same as java.util.regex, which is what I was using. In particular, the Jakarta package does not support any form of lookahead. (Compare org.apache.regexp.RE with java.util.regex.Pattern.) If you want to use Jakarta Regexp, you'll have to use my first suggestion, not the second.
I am using below regular expression in my application:
^([a-zA-Z0-9_\-\.&\*\+='/\{\}~]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$
But the limitation with this regex is that, it accepts dot(.) at the beginning, which is a wrong behaviour.
So can anyone please help me in updating this regex so that it should not accept (.) at its start.
Many Thanks
Gaurav
There is considerably more wrong with that regex than just the leading dot. For example
the IP address parts are allowed to be 999.
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Gaurav Sharma
Greenhorn
Joined: Jan 30, 2007
Posts: 28
posted
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Hi Simon,
I tried your first option & its working.
Now I am using :
^([a-zA-Z0-9_\-\&\*\+='/\{\}~][a-zA-Z0-9_\-\.&\*\+='/\{\}~]*)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$
It depends on how compliant you want your email addresses to be. The canonical email regex is this:You may or may not want to bother with being fully compliant.
See Mail-RFC822-Address. I use this example a lot when I think something should either (a) not be handled with regex, or (b) the focus should be on a smaller subset of the problem.
The regex for a full email address validation is very large. I published one in reply # 20 of here but I made it clear that it need a lot more testing before it should be used in production. I wrote that validator to validate RFC821 email addresses. I'm not sure what the latest RFC is but if you are to do it properly you need to find out. Having said that, you still have a problem. A lot of service providers allow email addresses to be outside the official specification so you might reject email addresses that are valid as far as your customer is concerned.
Many others have published email address regex validators of various conformance levels. Google will find them.
So why do you think you need to validate an email address? I used to think it necessary but these days I don't bother. If someone supplies aaaa@bbbb.ccc.ddd.ee your regex might accept it even though it is not going to exist.
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