I want to find potential US zip codes which are a string of 5 numbers, such as 12345 or 90210. The current regex I have uses alternation to get numbers of length 1-4 and then numbers of length 6+. Is there a better way to do this -- getting numbers of "all lengths except 5"?
^(?:[0-9]{0,4}|[0-9]{6,})$ (regex 101)You can use
^(?!\d{5}$)\d+$
See the regex demo and the regex graph:
Regex details:
^ - start of string(?!\d{5}$) - a negative lookahead that fails the match if there are any five digits immediately to the right of the current location till the end of string\d+ - one or more digits$ - end of string.If the numbers are to be matched in a longer text as separate matches, you may consider using word, or digit, or even whitespace boundaries:
\b(?!\d{5}\b)\d+ // word boundaries
(?<!\d)(?!\d{5}(?!\d))\d+ // digit boundaries
(?<!\S)(?!\d{5}(?!\S))\d+ // whitespace boundaries