title: String negation using regular expressions
body: <p>Is it possible to do string negation in regular expressions?  I need to match all strings that do not contain the string <code>".."</code>.  I know you can use <code>^[^\.]*$</code> to match all strings that do not contain <code>"."</code> but I need to match more than one character.  I know I could simply match a string containing <code>".."</code> and then negate the return value of the match to achieve the same result but I just wondered if it was possible.</p>