CODEWITHSUNDEEP
c#regex
user1428798
user1428798

Reputation: 1546

limit max length of mail address with regex + c#

I create a regex to validate email address this is my regex:

@"^\w+(\.?[-+\w])*@\w+([-.]\w+)*\.[a-zA-Z]{2,80}$"

I would like that the max length of the mail address is 80 but with this regex i only limit the last part of the mail after the .

Now 

aaa@aa.ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff is invalid

but 

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa@aa.ffffffff is valid

How can i do this?

Upvotes: 5

Views: 1708

Answers (3)

Alex Filipovici
Alex Filipovici

Reputation: 32561

Not sure if I made an obvious mistake, but I've made a test with a conditional expression with Yes and No clause. The test condition is the email format validation:

(?:^\w+\.?[-+\w]*@\w+(?:[-.]\w+)*\.[a-zA-Z]{2,}$)

If the condition is met, search the input for any character between 6 (the minimum length - [email protected]) and 80 repetitions:

^.{6,80}$

If the condition is not met, search again for the expression in the test condition (which produces no result):

^\w+\.?[-+\w]*@\w+(?:[-.]\w+)*\.[a-zA-Z]{2,}$

The whole regex looks like this:

(?(?:^\w+\.?[-+\w]*@\w+(?:[-.]\w+)*\.[a-zA-Z]{2,}$)^.{6,80}$|^\w+\.?[-+\w]*@\w+(?:[-.]\w+)*\.[a-zA-Z]{2,}$)

And it seems it's working.

Upvotes: 1

Thilina H
Thilina H

Reputation: 5804

You can validate within two steps.Just try it out. 

   Regex validCharsRegex = new Regex(@"^[\w!#$%&'*+\-/=?\^_`{|}~]+(\.[\w!#$%&'*+\-/=?\^_`{|}~]+)*" +
                                                      "@" + @"((([\-\w]+\.)+[a-zA-Z]{2,4})|(([0-9]{1,3}\.){3}[0-9]{1,3}))$");
   Match match = validCharsRegex.Match(stringText.Trim());
   if (match.Success && stringText.Length <=80 )
   {
     // You logic here
   }

Upvotes: 1

Stefano Bafaro
Stefano Bafaro

Reputation: 913

You can check sthe String.Lenght property to validate. If you wanna check the parts before and after the " @ " character, you can do a string.Split on character @ , and check the lenght of the 2 string resulting from the operation

Upvotes: 0

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