| . | Any Character | \d | digit; Note \ Escapes Special meaning |
|
| ? | Zero or 1 Time ab? is a or ab |
\D | Not a digit |
|
| + | One or More Ab+ is Ab Abb Abbb |
\s | Single White Space \s{2,3} is 2 or 3 White Spaces |
|
| * | Zero of More Ab* is A, Ab, ABB |
\S | Non White Space \S{3} match 3 non white spaces |
|
| ( ) | Word Delimiter | | | (abc)|(zyz) match abc or xyz | |
| {n} | Repeat A{2} matches AA |
\w | word variable identifier letter number underscore |
|
| ^ | Beginning of Line | [a-z] | Match lower case a-z | |
| $ | End of Line | [^a-z] | Match all but lower case a-z |