I have a regex, for example (ma|(t){1})
. It matches ma
and t
and doesn't match bla
.
I want to negate the regex, thus it must match bla
and not ma
and t
, by adding something to this regex. I know I can write bla
, the actual regex is however more complex.
This question is related to
regex
regex-negation
\b(?=\w)(?!(ma|(t){1}))\b(\w*)
this is for the given regex.
the \b is to find word boundary.
the positive look ahead (?=\w) is here to avoid spaces.
the negative look ahead over the original regex is to prevent matches of it.
and finally the (\w*) is to catch all the words that are left.
the group that will hold the words is group 3.
the simple (?!pattern) will not work as any sub-string will match
the simple ^(?!(?:m{2}|t)$).*$ will not work as it's granularity is full lines
Assuming you only want to disallow strings that match the regex completely (i.e., mmbla
is okay, but mm
isn't), this is what you want:
^(?!(?:m{2}|t)$).*$
(?!(?:m{2}|t)$)
is a negative lookahead; it says "starting from the current position, the next few characters are not mm
or t
, followed by the end of the string." The start anchor (^
) at the beginning ensures that the lookahead is applied at the beginning of the string. If that succeeds, the .*
goes ahead and consumes the string.
FYI, if you're using Java's matches()
method, you don't really need the the ^
and the final $
, but they don't do any harm. The $
inside the lookahead is required, though.
Apply this if you use laravel.
Laravel has a not_regex where field under validation must not match the given regular expression; uses the PHP preg_match
function internally.
'email' => 'not_regex:/^.+$/i'
Source: Stackoverflow.com