| Rule |
Syntax |
| Exactly one occurence of x |
x |
| At least one occurence of x |
x+ |
| 0 or many occurences of x |
x* |
| 0 or 1 occurence of x |
x? |
| Escape character |
\ |
| Any single character |
. |
| One character in a predefined set |
[list-of-characters] ... examples : [ABCD], [012345789] |
| One character in a character range |
[character1-character2] ... examples : [0-9], [a-zA-Z] ... |
| Any character except those contained in a predefined set |
[^list-of-characters] ... examples : [^ABCD], [^0-9] |
| Tab |
\t |
| New line |
\n |
| Carriage return |
\r |
| Beginning of the line |
^ |
| End of the line |
$ |