MWSoftware.org // Mike's Software

Character classes

.           any character except newline
\w \d \s    word, digit, whitespace
\W \D \S    not word, digit, whitespace
[abc]       any of a, b, or c
[^abc]      not a, b, or c
[a-g]       character between a & g

Anchors

^abc$       start / end of the string
\b          word boundary

Escaped Characters

\. \* \\    escaped special characters
\t \n \r    tab, linefeed, carriage return
\u0024      unicode escaped $

Groups & Lookaround

(abc)       capture group
\1          backreference to group #1
(?:abc)     non-capturing group
(?=abc)     positive lookahead
(?!abc)     negative lookahead

Quantifiers & Alternation

a* a+ a?    0 or more, 1 or more, 0 or 1
a{5} a{2,}  exactly five, two or more
a{1,3}      between one & three
a+? a{2,}?  match as few as possible
ab|cd       match ab or cd