النطاقات داخل الفئات: `[a-z0-9]`

Listing every character one by one is tedious. Classes accept ranges with the hyphen -: [a-z] matches any lowercase letter, [0-9] a digit, [A-Z] an uppercase letter.

Pattern: [a-z]+
Sample:  Ciao Mondo 123
          ^^^  ^^^^

The range uses code point order (essentially ASCII for Latin characters): a-z means "every character from the code point of a to the code point of z", so 26 letters.

Combining ranges

Inside a single class you can mix multiple ranges and individual characters:

[a-zA-Z0-9_]   identical to \\w (in ASCII)
[a-fA-F0-9]    hexadecimal digits
[0-9.]         digits or the dot (for decimal numbers)

Order does not matter: [0-9a-z] and [a-z0-9] are identical.

Ranges and ASCII character order

Ranges like [a-z] strictly follow the character order in the ASCII table. Writing an invalid range, such as [z-a], will trigger a regex compilation error. A literal dash should be placed at the start or end: [a-z-].

Try it

Review exercise

Additional challenge