Regular expression: validate email

Hi,


Give

\b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

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A try

http://www.regular-expressions.info/regexbuddy/email.html

//WebFooL Untangle Evangelist

try this:-

^((?>[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+\x20*|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*"\x20*)*(?<angle><))?((?!\.)(?>\.?[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+)+|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*")@(((?!-)[a-zA-Z\d\-]+(?<!-)\.)+[a-zA-Z]{2,}|\[(((?(?<!\[)\.)(25[0-5]|2[0-4]\d|[01]?\d?\d)){4}|[a-zA-Z\d\-]*[a-zA-Z\d]:((?=[\x01-\x7f])[^\\\[\]]|\\[\x01-\x7f])+)\])(?(angle)>)$

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http://regexlib.com/DisplayPatterns.aspx?AspxAutoDetectCookieSupport=1
http://www.codeproject.com/Articles/22777/Email-Address-Validation-Using-Regular-Expression

This one, as I posted, doesnt work. For example, I try test@i.com. It gets rejected by this

\b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

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The one posted by BuggyCoder doesnt work. I plug it in ASP.Net aspx page and there are characters that throw errors.

Should I be using the one Microsoft is using?

well well well, if you are using it in aspx page then do something like this:-

 public const string MatchEmailPattern =
                  @"^(([\w-]+\.)+[\w-]+|([a-zA-Z]{1}|[\w-]{2,}))@"
     + @"((([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?
                        [0-9]{1,2}|25[0-5]|2[0-4][0-9])\."
     + @"([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?
                        [0-9]{1,2}|25[0-5]|2[0-4][0-9])){1}|"
     + @"([a-zA-Z]+[\w-]+\.)+[a-zA-Z]{2,4})$";

just add @ before string, i hope you are using c#.
Try visiting this link:-
http://www.codeproject.com/Articles/22777/Email-Address-Validation-Using-Regular-Expression

i am using C# but what you have throws errors. This is what i have now:

<asp:RegularExpressionValidator  ID="RegularExpressionValidator1" runat="server"  
                                      
                                     Text="Invalid email address!"
                                    ErrorMessage="Invalid email address!" 
                                    ControlToValidate="txtEmail"     
                                    ValidationExpression="\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"/>

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Yes, i saw that link as well. But there has a be a better way of doing this. How's the performance of using such a long regualr expression??

this is the one i found on MSDN:-

^(?("")("".+?""@)|(([0-9a-zA-Z]((\.(?!\.))|[-!#\$%&'\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-zA-Z])@))(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,6}))$

try to add escape characters when you wrap it in a string variable on in control parameter........ or simply replace  " with '(single quote)

I changed double quotes to single but get syntax error. Not sure what you mean by escape characters...

 ValidationExpression="^(?('')(''.+?''@)|(([0-9a-zA-Z]((\.(?!\.))|[-!#\$%&'\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-zA-Z])@))(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,6}))$"/>

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You might find this article interesting: http://www.regular-expressions.info/email.html

It's the same site as WebF00L's link, but with explanations.

here have a look at what are escape sequences or characters:-
http://msdn.microsoft.com/en-us/library/ms228362.aspx

you think i should use that one? test@i.com is not valid probably because of "i.com"....that probably below doesnt allow:

\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

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Or should I stick with what MS has but it allows stuff like 123@4.3

ValidationExpression="\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"/>

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Maybe you should ask yourself what are the consequences of an invalid email address? If you have users setting up an account of some sort, it's a common technique to send an email to them to validate it's really them. Otherwise even a valid email address may not have the desired person at the other end.

Terry, you think i should stick with what MS has in their site?
ValidationExpression="\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"/>

We won't use the email to send validation emails. It's just to have the user's email address. I think it would be ok to keep the same regualr expression that MS has, correct?

let me try that.

The latest one accepts 123@4.5  and I'm assuming it's ok because I want it to be flexible. Correct?

Yes.