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To match any character except a list of excluded characters, put the excluded charaters between [^ and ] . The caret ^ must immediately follow the [ or else it stands for just itself. The character '. ' (period) is a metacharacter (it sometimes has a special meaning).
Non-capturing groups are important constructs within Java Regular Expressions. They create a sub-pattern that functions as a single unit but does not save the matched character sequence. In this tutorial, we'll explore how to use non-capturing groups in Java Regular Expressions.
Match a white space followed by one or more decimal digits, followed by zero or one period or comma, followed by zero or more decimal digits. This is the first capturing group. Because the replacement pattern is $1 , the call to the Regex. Replace method replaces the entire matched substring with this captured group.
Line breaks In pattern matching, the symbols “^” and “$” match the beginning and end of the full file, not the beginning and end of a line. If you want to indicate a line break when you construct your RegEx, use the sequence “\r\n”.
The only way not to capture something is using look-around assertions:
(?<=123-)((apple|banana)(?=-456)|(?=456))
Because even with non-capturing groups (?:…) the whole regular expression captures their matched contents. But this regular expression matches only apple or banana if it’s preceded by 123- and followed by -456, or it matches the empty string if it’s preceded by 123- and followed by 456.
| Lookaround | Name | What it Does |
|---|---|---|
| (?=foo) | Lookahead | Asserts that what immediately FOLLOWS the current position in the string is foo |
| (?<=foo) | Lookbehind | Asserts that what immediately PRECEDES the current position in the string is foo |
| (?!foo) | Negative Lookahead | Asserts that what immediately FOLLOWS the current position in the string is NOT foo |
| (?<!foo) | Negative Lookbehind | Asserts that what immediately PRECEDES the current position in the string is NOT foo |
Update: Thanks to Germán Rodríguez Herrera!
In javascript try: /123-(apple(?=-)|banana(?=-)|(?!-))-?456/
Remember that the result is in group 1
Debuggex Demo
Try:
123-(?:(apple|banana|)-|)456
That will match apple, banana, or a blank string, and following it there will be a 0 or 1 hyphens. I was wrong about not having a need for a capturing group. Silly me.
I have modified one of the answers (by @op1ekun):
123-(apple(?=-)|banana(?=-)|(?!-))-?456
The reason is that the answer from @op1ekun also matches "123-apple456", without the hyphen after apple.
Try this:
/\d{3}-(?:(apple|banana)-)?\d{3}/
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