Like most regex flavors, java.util.regex.Pattern has its own specific features with syntax that may not be fully compatible with others; this includes character class union, intersection and subtraction: [a-d[m-p]] : a through d, or m through p: [a-dm-p] (union) [a-z&&[def]] : d, e, or f (intersection) [a-z&&[^bc]] : a through z, except for b and … Read more
Use a negated class including \W or \S. /[^\W_]/ # anything that’s not a non-word character and not _ /[^\S\t]/ # anything that’s not a non-space character and not \t
\p{L} matches a single code point in the category “letter”. \p{N} matches any kind of numeric character in any script. Source: regular-expressions.info If you’re going to work with regular expressions a lot, I’d suggest bookmarking that site, it’s very useful.
This is because the “OR” construct | backtracks between the alternation: If the first alternation is not matched, the engine has to return before the pointer location moved during the match of the alternation, to continue matching the next alternation; Whereas the character class can advance sequentially. See this match on a regex engine with … Read more
It really depends on your regex flavor. .NET … provides only one simple character class set operation: subtraction. This is enough for your example, so you can simply use [\w-[_]] If a – is followed by a nested character class, it’s subtracted. Simple as that… Java … provides a much richer set of character class … Read more