Match an email address if it contains a dot

Question

I want to match any email address, that contains at least one . (dot) before the @ sign. The emails have already been validated, so the regex just needs to search for the ..

I have tried

Regex emailMatcher = new Regex(@"^[a-zA-Z\.']{1,}\.[a-zA-Z\.']{1,}@example\.com$");

But I know that emails can contain more characters than just a-zA-Z\.' so this won't cover all cases.

Any ideas on how to do it?

Thanks

EDIT: I'm not trying to validate emails, I already have the emails validated, I just need to select emails, that contain . before @ sign

Examples that would pass:

[email protected]
[email protected]

Examples that should pass, but wouldn't pass using my current regex

first.last(comment)@example.com

Answer 1

You could do this without a regex

Func<string, bool> dotBeforeAt = delegate(string email) 
{ 
    var dotIndex = email.IndexOf(".");
    return dotIndex > -1 && (dotIndex < email.IndexOf("@"));
};
...
emails.Where(dotBeforeAt).ToList();

Try it out

Answer 2

I just need to select ones, that contain dot before @ sign

Then there is no point to build a regex that matches valid e-mail addresses. All you need is a regex that sees that there is a dot in front of the @ sign:

(?<=[.][^@]*)@

(?<=[.][^@]*) is a positive lookbehind construct. It ensures that the @ sign following it is matched only when there is a dot [.] followed by zero or more non-@ characters in front of it.