just text: matches any string with the given text inside it
^ matches string that starts with the given text
$ matches string that ends with the given text
* zero or more
+ one or more
? zero or one
{n} n occurrences
a|b or [ab] a or b
\d matches a digit
\w matches a word character (alphanumeric plus underscore)
\s matches a whitespace character
. matches any character
Anchors
just text
abc matches any string that has the text abc in it
^
^abc matches any string that starts with abc
$
abc$ matches any string that ends with abc
exact match
^abc$ matches only the exact string abc
Quantifiers
*
abc* matches any string containing ab followed by any number of c s
+
abc+ matches any string containing ab followed by at least one c
?
abc? matches any string containing ab followed by at the most one c
{n}
abc{2} matches any string containing ab followed by two c s
abc{2,} matches any string containing ab followed by two or more c s
abc{2,5} matches any string containing ab followed by between two and five c s
OR operator
a|b a or b
[abc] a or b or c
Character classes
\d
\d matches any character in a string that is a digit
\D matches any character that isn’t a digit
\w
\w matches any character in a string that is a word character
\W matches any character that isn’t a word character
\s
\s matches any whitespace character in a string
\S matches any non-whitespace character
.
. matches any character in a string