Regex for an email address doesn't work

Question

Hi,

I'm trying to check if some email address is correct with the following code :

NSPredicate *regexMail = [NSPredicate predicateWithFormat:@"SELF MATCHES '.*@.*\..*'"];
if([regexMail evaluateWithObject:someMail])
... 

But the "\." doesn't seem to work since the mail "smith@company" is accepted. Besides, I have the following warning : "Unknown escape sequence"

Edit :

I'm programming in Objective-C for iPhone.

Thanks

Answer 1

I guess it should be \\., since \ itself should be escaped as well.

Answer 2

try putting double slash instead of one slash. that's what might the Unknown escape sequence mean.

here is a website that can help you understand how to use regex: http://www.wellho.net/regex/java.html

or just find the appropriate regex for email address here: http://regexlib.com/DisplayPatterns.aspx?cattabindex=0&categoryId=1

Answer 3

You cannot correctly validate an email address with regular expressions alone. A simple search will show you many articles discussing this. The problem lies with the nature of DNS: there are too many possible domain names (including non-english and Unicode domains), you cannot correctly validate them using a regex. Don't try.

The only correct way to determine if an email address is valid is to send a message to the address with a unique URL that identifies the account associated with the email, for the user to click. Anything else will annoy your end-user.

Answer 4

I think youre looking for this. Its a quite comprehensive listing of different regexps and a list of mail addresses for each, stating if the regexp was successful or not.

Answer 5

Here's a working example, with a slightly more appropriate pattern (although it's not perfect, as others have mentioned):

NSString* pattern = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern];
if ([predicate evaluateWithObject:@"[email protected]"] == YES) {
  // Match
} else {
  // No Match
}