Regex problem: IsMatch method never returns

Question

I have a regex issue that I need help with. Its trying to validate an Email address.

Regex rx = new Regex(@"^[A-Za-z0-9]([_\.\-]?[A-Za-z0-9]+)*\@[A-Za-z0-9]([_\.\-]?[A-Za-z0-9]+)*\.[A-Za-z0-9]([_\.\-]?[A-Za-z0-9]+)*$|^$");
rx.IsMatch("john.gilbert.stu.seattle.washington.us"); 

The IsMatch method never returns for that particular string. It goes into some infinite loop. Can anybody see what the problem is with the pattern.

Thanks!

Answer 1

(some stuff)* is bad. See here: http://www.regular-expressions.info/catastrophic.html

Answer 2

I would recommend you the following to validate an email address:

try
{
    MailAddress addr = new MailAddress("[email protected]");
}
catch (FormatException exc)
{
    // The email address is not valid
}

Here's an interesting read.

Answer 3

The first "+" is the problem, if you remove it it runs