| Regular Expression Basics |
|---|
| . |
Any character except newline |
| a |
The character a |
| ab |
The string ab |
| a|b |
a or b |
| a* |
0 or more a‘s |
| \ |
Escapes a special character |
| Regular Expression Quantifiers |
|---|
| * |
0 or more |
| + |
1 or more |
| ? |
0 or 1 |
| {2} |
Exactly 2 |
| {2, 5} |
Between 2 and 5 |
| {2,} |
2 or more |
| Default is greedy. Append ? for reluctant. |
| Regular Expression Groups |
|---|
| (...) |
Capturing group |
| (?:...) |
Non-capturing group |
| \Y |
Match the Y‘th captured group |
|
| Regular Expression Character Classes |
|---|
| [ab-d] |
One character of: a, b, c, d |
| [^ab-d] |
One character except: a, b, c, d |
| [\b] |
Backspace character |
| \d |
One digit |
| \D |
One non-digit |
| \s |
One whitespace |
| \S |
One non-whitespace |
| \w |
One word character |
| \W |
One non-word character |
| Regular Expression Assertions |
|---|
| ^ |
Start of string |
| $ |
End of string |
| \b |
Word boundary |
| \B |
Non-word boundary |
| (?=...) |
Positive lookahead |
| (?!...) |
Negative lookahead |
|
| Regular Expression Flags |
|---|
| g |
Global Match |
| i |
Ignore case |
| m |
^ and $ match start and end of line |
| Regular Expression Special Characters |
|---|
| \n |
Newline |
| \r |
Carriage return |
| \t |
Tab |
| \0 |
Null character |
| \YYY |
Octal character YYY |
| \xYY |
Hexadecimal character YY |
| \uYYYY |
Hexadecimal character YYYY |
| \cY |
Control character Y |
| Regular Expression Replacement |
|---|
| $$ |
Inserts $ |
| $& |
Insert entire match |
| $` |
Insert preceding string |
| $‘ |
Insert following string |
| $Y |
Insert Y‘th captured group |
|
