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Regex not operator

Is there an NOT operator in Regexes? Like in that string : "(2001) (asdf) (dasd1123_asd 21.01.2011 zqge)(dzqge) name (20019)"

I want to delete all \([0-9a-zA-z _\.\-:]*\) but not the one where it is a year: (2001).

So what the regex should return must be: (2001) name.

NOTE: something like \((?![\d]){4}[0-9a-zA-z _\.\-:]*\) does not work for me (the (20019) somehow also matches...)

Solution

  • No, there's no direct not operator. At least not the way you hope for.

    You can use a zero-width negative lookahead, however:

    \((?!2001)[0-9a-zA-z _\.\-:]*\)

    The (?!...) part means "only match if the text following (hence: lookahead) this doesn't (hence: negative) match this. But it doesn't actually consume the characters it matches (hence: zero-width).

    There are actually 4 combinations of lookarounds with 2 axes:

    • lookbehind / lookahead : specifies if the characters before or after the point are considered
    • positive / negative : specifies if the characters must match or must not match.