# regex quick reference

| Example    | Description                                    |
|------------|------------------------------------------------|
| `[abc]`    | A single character of: a, b, or c              |
| `[^abc]`   | Any single character except: a, b, or c        |
| `[a-z]`    | Any single character in the range a-z          |
| `[a-zA-Z]` | Any single character in the range a-z or A-Z   |
| `^`        | Start of line                                  |
| `$`        | End of line                                    |
| `\A`       | Start of string                                |
| `\z`       | End of string                                  |
| `.`        | Any single character                           |
| `\s`       | Any whitespace character                       |
| `\S`       | Any non-whitespace character                   |
| `\d`       | Any digit                                      |
| `\D`       | Any non-digit                                  |
| `\w`       | Any word character (letter, number, underscore)|
| `\W`       | Any non-word character                         |
| `\b`       | Any word boundary                              |
| `(a\|b)`   |a or b                                          |
| `a?`       | Zero or one of a                               |
| `a*`       | Zero or more of a                              |
| `a+`       | One or more of a                               |
| `a{3}`     | Exactly 3 of a                                 |
| `a{3,}`    | 3 or more of a                                 |
| `a{3,6}`   | Between 3 and 6 of a                           |
| `\`        | Escape character                               |