The metacharacters [ and ] sets specify a character class inside a regular expression.
A character class is a set of characters.
The regular expression tries to match one character from the set.
The character class "[ABC]" will match characters A, B, or C.
strings "A@V", "B@V", and "C@V" will match the regular expression "[ABC]@.".
string "H@V" will not match the regular expression "[ABC]@." because @ is not preceded by A, B, or C.
strings "man" or "men" will match the regular expression "m[ae]n".
To specify a range of characters using a character class, use a hyphen - character. For example,
^ in the beginning of a character class negates the meaning. For example,
If you use ^ anywhere in a character class except in the beginning, it loses its special meaning and it matches just a ^ character.
For example, "[ABC^]" will match A, B, C, or ^.
You can include two or more ranges in one character class. For example,
Some examples of character classes are listed in the following table.
|Character Classes|| Meaning|| Category|
|[abc]|| Character a, b, or c|| Simple character class|
|[^xyz]|| A character except x, y, and z|| Complement or negation|
|[a-p]|| Characters a through p|| Range|
|[a-cx-z]|| Characters a through c, or x through z, which would|
include a, b, c, x, y, or z.
|[0-9&&[4-8]]|| Intersection of two ranges (4, 5, 6, 7, or 8)|| Intersection|
|[a-z&&[^aeiou]]|| All lowercase letters minus vowels. In other words, a lowercase |
letter, which is not a vowel. That is, all lowercase consonants.