§Meta characters
([{\^$|)?*+
•Escape meta character
\
\Q\E
§Classes
are enclosed within []
•Simple class
[abc]: a, b, or c
•Negation
[^abc]: any character except a,b,c
•Ranges
[a-c]: character a to c
•Unions
[0-4[6-8]]
•Intersections
[0-9&&[345]]: 3,4,5
•Substraction
[0-9&&[^345]]: except 3,4,5
§Predefined character classes
. any character
\d a digit [0-9]
\D a non digit [^0-9]
\s a whitespace character
\S a non-whitespace character
\w a word character [a-zA-Z_0-9]
\W a non-word character[^\w]
§Qualifiers
greedy reluctant possessive
x? x?? x?+
X*
x+
x{n}
x{n,}
x{n,m}
§Capturinq groups
()
§Back reference
(\d\d)\1
§Boundary Matchers
^ begin of a line
$ end of a line
\b a word boundary
\B a non-word boundary
\A beqin of the input
\G end of previous match
\Z end of the input but for the final terminator, if any
\z end of input