问题
I'm looking to construct a regex which will help me identify the first occurrence of a match.
My current regex is "(.*)[Cc][Aa][Ss][Ee][^a-zA-Z\\d]*(\\d\\d*)[^a-zA-Z\\d]*(.*)"
What I am trying to do is to find if the input string contains the word "case" (case insensitive), followed by any number of special characters, followed by a number;
I want to retrieve 3 parts of the text.
Say my input string is "RE: FW: case:-1234: there is some description"
Using this regex, I am able to retrieve, "RE: FW: ", "1234", "there is some description".
This is fine, but if my input string is
"RE: FW: case:-1234: This is in reference to case 789 reopening"
Then my regex returns, "RE: FW: case:-1234: This is in reference to", "789", "reopening".
What I would like to get is "RE: FW: ", "1234", "This is in reference to case 789 reopening".
I am a newbie with regex, so any help is much appreciated.
Note: I am working on a java based tool, so java compatible regex would be nice.
回答1:
Does your regex have to match the entire string (i.e. does it use matches)? If not (or if you can choose to use find instead) simply remove the (.*), because that's what pushes your match back:
[Cc][Aa][Ss][Ee][^a-zA-Z\\d]*(\\d\\d*)[^a-zA-Z\\d]*
Otherwise, make the leading repetition non-greedy;
(.*?)[Cc][Aa][Ss][Ee][^a-zA-Z\\d]*(\\d\\d*)[^a-zA-Z\\d]*(.*)
By the way, you can simplify this, using case-insensitive matching. If you cannot activate it in your tool, you can do it inline in the regex:
(?i)(.*?)case[^a-z\\d]*(\\d+)[^a-z\\d]*(.*)
Note that I also simplified the number. + means 1 or more occurrence.
回答2:
You were missing ?
Your regex would be
(?i)(.*?)case[^a-z\d]*(\d+)(.*)
You can toggle case insensitive match using (?i) in regex
来源：https://stackoverflow.com/questions/17466927/regex-to-match-only-till-first-occurence-of-class-match