Is it possible to do string negation in regular expressions? I need to match all strings that do not contain the string "..". I know you can use ^[^\.]*$ to match all strings that do not contain "." but I need to match more than one character. I know I could simply match a string containing ".." and then negate the return value of the match to achieve the same result but I just wondered if it was possible.
You can use negative lookaheads:
^(?!.*\.\.).*$
That causes the expression to not match if it can find a sequence of two periods anywhere in the string.
^(?:(?!\.\.).)*$
will only match if there are no two consecutive dots anywhere in the string.
来源：https://stackoverflow.com/questions/1153856/string-negation-using-regular-expressions