问题
I'm using rubular.com to build my regex, and their documentation describes the following:
(...) Capture everything enclosed
(a|b) a or b
How can I use an OR expression without capturing what's in it? For example, say I want to capture either "ac" or "bc". I can't use the regex
(a|b)(c)
right? Since then I capture either "a" or "b" in one group and "c" in another, not the same. I know I can filter through the captured results, but that seems like more work...
Am I missing something obvious? I'm using this in Java, if that is pertinent.
回答1:
Depending on the regular expression implementation you can use so called non-capturing groups with the syntax (?:…):
((?:a|b)c)
Here (?:a|b) is a group but you cannot reference its match. So you can only reference the match of ((?:a|b)c) that is either ac or bc.
回答2:
If your implementation has it, then you can use non-capturing parentheses:
(?:a|b)
回答3:
Even rubular doesn't make you use parentheses and the precedence of | is low. For example a|bc does not match ccc
来源：https://stackoverflow.com/questions/3378773/can-i-use-an-or-in-regex-without-capturing-whats-enclosed