Regular Expression Cheat Sheet

Last updated on 2023-05-03 | Edit this page

[] defines a range of characters.
. matches any character.
\ is used to escape the following character when that character is a special character. So, for example, a regular expression that found ‘.com’ would be \\.com because . is a special character that matches any character.
\d matches any single digit.
\w matches any part of word character (equivalent to [A-Za-z0-9]).
\s matches any space, tab, or newline.
^ asserts the position at the start of the line. So what you put after it will only match if they are the first characters of a line.
$ asserts the position at the end of the line. So what you put before it will only match if they are the last characters of a line.
\b adds a word boundary. Putting this either side of a word stops the regular expression matching longer variants of words.
* matches the preceding element zero or more times. For example, ab*c matches ‘ac’, ‘abc’, ‘abbbc’, etc.
+ matches the preceding element one or more times. For example, ab+c matches ‘abc’, ‘abbbc’ but not ‘ac’.
? matches when the preceding character appears zero or one time.
{VALUE} matches the preceding character the number of times define by VALUE; ranges can be specified with the syntax {VALUE,VALUE}.
| means or.