I am trying to figure out a regular expression that selects all words that do NOT begin with one of a set of prefixes.
For example, with allowable word prefixes jan|feb|mar|apr I'd want to match the text in bold in the following string:
"in january or feb I marched off to see april"
I managed to select the exact opposite of what I'd like, matching words beginning with the prefixes:
(?:jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)(?:\w )?
I also managed to select all words that were not the prefixes themselves, but this doesn't handle all words beginning with the prefixes, just words that are the prefix:
[a-z] \b(?<!\bjan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)
The ultimate goal is to strip all words that do not begin with one of the prefixes from the input string.
CodePudding user response：
The ultimate goal is to strip all words that do not begin with one of the prefixes from the input string.
You may use this regex for matching:
\b(?!(?:jan|feb|mar|apr|may|ju[nl]|aug|sep|oct|nov|dec))\w \s*
and replace it with an empty string.
RegEx Details:
\b: Word boundary(?!: Start negative lookahead(?:jan|feb|mar|apr|may|ju[nl]|aug|sep|oct|nov|dec): Match of the 3 letter month prefix
): End negative lookahead\w: Match 1 word characters\s*: Match 0 or more whitespaces