نفی: `[^...]`

Placing a caret ^ as the first character inside brackets inverts the class: it matches any character except those listed.

Pattern: [^aeiou]
Sample:  ciao mondo
          ^   ^^  ^

[^aeiou] matches consonants, spaces, punctuation, digits\u2026 everything that is not a vowel.

Typical examples

• [^\s] -- any "non-space" character (equivalent to \S).
• [^0-9] -- anything that is not a digit (equivalent to \D).
• [^"]+ -- "a sequence of characters that are not double quotes" (useful to extract content between quotes).

Pattern: "([^"]+)"
Sample:  Il libro "Il nome della rosa" e' famoso.

The group ([^"]+) captures everything between quotes stopping before the next ": it is a classic trick to avoid the greedy-vs-lazy problem.

Negation and alternative wildcards

The negated class [^...] consumes exactly one character that is NOT part of the listed set. It is a powerful tool to prevent the engine from running past critical delimiters, avoiding ReDoS caused by infinite backtracking loops.

Try it

Review exercise

Additional challenge