问题
I am writing a regex that will be used for recognizing commands in a string. I have three possible words the commands could start with and they always end with a semi-colon.
I believe the regex pattern should look something like this:
(command1|command2|command3).+;
The problem, I have found, is that since . matches any character and + tells it to match one or more, it skips right over the first instance of a semi-colon and continues going.
Is there a way to get it to stop at the first instance of a semi-colon it comes across? Is there something other than . that I should be using instead?
回答1:
The issue you are facing with this: (command1|command2|command3).+; is that the + is greedy, meaning that it will match everything till the last value.
To fix this, you will need to make it non-greedy, and to do that you need to add the ? operator, like so: (command1|command2|command3).+?;
Just as an FYI, the same applies for the * operator. Adding a ? will make it non greedy.
回答2:
Tell it to find only non-semicolons.
[^;]+
回答3:
What you are looking for is a non-greedy match.
.+?
The "?" after your greedy + quantifier will make it match as less as possible, instead of as much as possible, which it does by default.
Your regex would be
'(command1|command2|command3).+?;'
See Python RE documentation
来源：https://stackoverflow.com/questions/13005815/match-any-characters-more-than-once-but-stop-at-a-given-character