I recently reviewed a pull request with a few commits focused on regular expression code changes. It's time to re-create a quick regular expression cheat sheet.
Common expressions
Category | Expression | Description |
---|---|---|
Special Characters | . \n \f \t \xhhhh |
any character newline character form feed character tab character Unicode character defined by hexadecimal number, i.e. \xFFFF |
Quantifiers | + ? * {x,y} |
1 or more 0 or one 0 or more at least ‘x’ but no more that ‘y’ occurrences |
Character Sets | \s \S \d \D \w \W [a-x] [^a-x] |
whitespace character non-whitespace character digit character (0-9) non-digit character any letter or digit or underscore (_) character non-word character characters in the range of a to x, excluding yz characters except in the range of a to x, i.e. y and z |
Anchoring | ^ $ \b \B |
if the first character, indicates that the match starts at beginning of string Match must continue to end of string word boundary non-word boundary |
An example

- The first character ^ indicates that the next match (19|20) starts at beginning of string.
- We either need a 19 or a 20 at the beginning of the string.
- Next we have two digit character (0-9).
- Next we have a range of valid characters, in this case minus, slash, space and dot.
- Next we have two possible combinations of digits.
5.1 Either we have a 0, followed by a digit in the range of 1-9, i.e. 01 to 09.
5.2 Or we have a 1, followed by a zero, one or two, i.e. 10, 11 or 12. - The last character $ indicates that the next match must continue to end of string.
- Next we have three possible combinations of digits.
7.1 Either we have a 0, followed by a digit in the range of 1-9, i.e. 01 to 09.
7.2 Or we have a 1 or a 2, followed by a digit in the range of 0-9, i.e. 10 to 29.
7.3 Or we have a three, followed by a zero or a one, i.e. 30 - 31.
If you need more examples, go to regularexpressions.info.